Method and system for alternative absolute profile determination

ABSTRACT

The invention relates to a processing system. The processing system includes a sensor module performing a first measurement to obtain a combination signal using a first sensor electrode and a second sensor electrode. The first electrode is driven using a first modulated signal with a first driving voltage amplitude and simultaneously the second electrode is driven using a second modulated signal with a second driving voltage amplitude greater than the first driving voltage amplitude, while simultaneously first and second resulting signals are received from the first and second electrodes, respectively. The sensor module is further performs a second measurement to obtain a transcapacitance signal using the first and second sensor electrodes. The processing system also includes a determination module that generates the combination signal by combining the first and second resulting signals, and computes an absolute capacitance signal from the combination signal, the transcapacitance signal, and a background capacitance.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Application No. 62/547,603, filed on Aug. 18, 2017, havingat least one of the same inventors as the present application, andentitled, “METHODS AND SYSTEMS FOR USING TABS PROFILES BASED ON LOWGROUND MASS CONDITIONS”. U.S. Provisional Application No. 62/547,603 isincorporated herein by reference.

FIELD

This disclosed technology generally relates to electronic devices andspecifically to capacitive sensing profiles.

BACKGROUND

Input devices including proximity sensor devices (also commonly calledtouchpads or touch sensor devices) are widely used in a variety ofelectronic systems. A proximity sensor device typically includes asensing region, often demarked by a surface, in which the proximitysensor device determines the presence, location and/or motion of one ormore input objects. Proximity sensor devices may be used to provideinterfaces for the electronic system. For example, proximity sensordevices are often used as input devices for larger computing systems(such as opaque touchpads integrated in, or peripheral to, notebook ordesktop computers). Proximity sensor devices are also often used insmaller computing systems (such as touch screens integrated in cellularphones and tablet computers). Such touch screen input devices aretypically superimposed upon or otherwise collocated with a display ofthe electronic system.

SUMMARY

In general, in one aspect, one or more embodiments relate to aprocessing system. The processing system includes a sensor module, thesensor module configured to perform a first measurement to obtain acombination signal using a first sensor electrode and a second sensorelectrode among a plurality of sensor electrodes by selecting a firstdriving voltage amplitude for the first sensor electrode and a seconddriving voltage amplitude for the second sensor electrode, wherein thesecond driving voltage amplitude is greater than the first drivingvoltage amplitude, driving the first electrode using a first modulatedsignal with the first driving voltage amplitude and simultaneouslydriving the second electrode using a second modulated signal with thesecond driving voltage amplitude, and receiving, simultaneously with thedriving of the first and the second electrodes, a first resulting signalfrom the first electrode and a second resulting signal from the secondelectrode. The sensor module is further configured to perform a secondmeasurement to obtain a transcapacitance signal using the first and thesecond sensor electrodes. The processing system also includes adetermination module, the determination module configured to generatethe combination signal by combining the first and the second resultingsignals, and compute an absolute capacitance signal from the combinationsignal, the transcapacitance signal, and a background capacitance.

In general, in one aspect, one or more embodiments relate to acapacitive sensing input device. The capacitive sensing input deviceincludes a plurality of sensor electrodes disposed in a sensor electrodepattern, the plurality of sensor electrodes including a first sensorelectrode and a second sensor electrode. The capacitive sensing inputdevice further includes a sensor module, the sensor module configured toperform a first measurement to obtain a combination signal using thefirst sensor electrode and the second sensor electrode by selecting afirst driving voltage amplitude for the first sensor electrode and asecond driving voltage amplitude for the second sensor electrode,wherein the second driving voltage amplitude is greater than the firstdriving voltage amplitude, driving the first electrode using a firstmodulated signal with the first driving voltage amplitude andsimultaneously driving the second electrode using a second modulatedsignal with the second driving voltage amplitude, and receiving,simultaneously with the driving of the first and the second electrodes,a first resulting signal from the first electrode and a second resultingsignal from the second electrode. The sensor module is furtherconfigured to perform a second measurement to obtain a transcapacitancesignal using the first and the second sensor electrodes. The capacitivesensing input device also includes a determination module, thedetermination module configured to generate the combination signal bycombining the first and the second resulting signals, and compute anabsolute capacitance signal from the combination signal, thetranscapacitance signal, and a background capacitance.

In general, in one aspect, one or more embodiments relate to a method ofcapacitive sensing. The method includes performing a first measurementto obtain a combination signal from a first sensor electrode and asecond sensor electrode among a plurality of sensor electrodes by:selecting a first driving voltage amplitude for the first sensorelectrode and a second driving voltage amplitude for the second sensorelectrode, wherein the second driving voltage amplitude is greater thanthe first driving voltage amplitude, driving the first electrode using afirst modulated signal with the first driving voltage amplitude andsimultaneously driving the second electrode using a second modulatedsignal with the second driving voltage amplitude, and receiving,simultaneously with the driving of the first and the second electrodes,a first resulting signal from the first electrode and a second resultingsignal from the second electrode. The method further includes performinga second measurement to obtain a transcapacitance signal using the firstand the second sensor electrodes, generating the combination signal bycombining the first and the second resulting signals, and computing anabsolute capacitance signal from the combination signal, thetranscapacitance signal, and a background capacitance.

BRIEF DESCRIPTION OF DRAWINGS

The drawings referred to in this Brief Description of Drawings shouldnot be understood as being drawn to scale unless specifically noted. Theaccompanying drawings, which are incorporated in and form a part of theDescription of Embodiments, illustrate various embodiments and, togetherwith the Description of Embodiments, serve to explain principlesdiscussed below, where like designations denote like elements.

FIG. 1 is a block diagram of an example input device, in accordance withembodiments.

FIG. 2A shows a portion of an example sensor electrode pattern which maybe utilized in a sensor to generate all or part of the sensing region ofan input device, such as a touch screen, according to some embodiments.

FIG. 2B illustrates an example matrix array of sensor electrodes,according to various embodiments.

FIG. 3A shows more detailed block diagram of the input device of FIG. 1,according to an embodiment.

FIG. 3B shows an exploded side sectional view of a portion of the inputdevice of FIG. 3A, according to an embodiment.

FIG. 4 shows a matrix of capacitances associated with the input deviceillustrated in FIGS. 3A and 3B, according to an embodiment.

FIG. 5 shows a block diagram of an example processing system, accordingto an embodiment.

FIG. 6A shows an exploded front side elevation of the example sensorelectrode pattern of FIG. 2A with labeled capacitances, according to anembodiment.

FIG. 6B shows an exploded left side elevation of the example sensorelectrode pattern of FIG. 2A with labeled capacitances, according to anembodiment.

FIG. 6C shows an exploded front side elevation of the example sensorelectrode pattern of FIG. 2A with labeled capacitances, according to anembodiment.

FIG. 6D shows an exploded left side elevation of the example sensorelectrode pattern of FIG. 2A with labeled capacitances, according to anembodiment.

FIGS. 7A, 7B, 7C, 7D, 7E, 7F, and 7G show a flow diagram of an examplemethod of capacitive sensing, according to various embodiments.

FIG. 8 shows a capacitive diagram in accordance with one or moreembodiments.

FIG. 9 shows a flowchart describing a method for alternative absoluteprofile determination, in accordance with one or more embodiments.

FIG. 10 shows a flowchart describing a method for obtaining acombination signal, in accordance with one or more embodiments.

FIG. 11 shows a flowchart describing a method for obtaining atranscapacitance signal, in accordance with one or more embodiments.

FIG. 12 shows a capacitive diagram in accordance with one or moreembodiments.

FIG. 13 shows exemplary sensing profiles in accordance with one or moreembodiments.

FIG. 14 shows a computing system in accordance with one or moreembodiments.

DESCRIPTION OF EMBODIMENTS

The following Description of Embodiments is merely provided by way ofexample and not of limitation. Furthermore, there is no intention to bebound by any expressed or implied theory presented in the precedingBackground, Summary, or Brief Description of Drawings or the followingDescription of Embodiments.

Overview of Discussion

Herein, various embodiments are described that provide input devices,processing systems, and methods that facilitate improved usability. Invarious embodiments described herein, the input device may be acapacitive sensing input device. In general, conventional capacitancesensing measures substantially one type of capacitance at a time withsensor electrodes of a sensor electrode pattern, typically either anabsolute capacitance associated with a sensor electrode or atranscapacitance measured between two non-parallel sensor electrodes.Absolute capacitance signals may be used in various scenarios, includingthe detection of certain sensing conditions such as low ground mass(LGM) conditions. Accordingly, the availability of absolute capacitancesignals may be beneficial. However, in traditionally performed absolutecapacitance measurements, a parasitic background capacitance may beorders of magnitude larger than the capacitance cause by an input objectsuch as a finger. As a result, relatively high charges may be requiredto perform absolute capacitance measurements, while only a smallfraction of the overall charge may be associated with the presence ofthe input object. As a result, absolute capacitance measurements maybecome inaccurate, and/or it may become challenging for the sensingcircuitry to handle the necessary level of charge without saturating.

In one or more embodiments, to avoid the requirement for high charges,an absolute capacitance measurement is indirectly obtained byreconstruction from a combination capacitive sensing measurement. Ingeneral, combined capacitive sensing, as described herein, involvesusing a sensor electrode pattern to make numerous different types ofcapacitive measurements simultaneously (e.g., simultaneous measurementof absolute capacitance and one or more types of transcapacitance) suchthat the effect of user input on the different types of measurements maybe used to determine a reported position of an input object or userinterface response in response to user input.

Discussion begins with a description of an example input device withwhich or upon which various embodiments described herein may beimplemented. An example sensor electrode pattern is then described. Ageneral description of techniques for combined capacitive sensing with asensor electrode pattern is provided along with some examples. This isfollowed by description of an example processing system and somecomponents thereof which may be utilized for combined capacitivesensing. The processing system may be utilized with or as a portion ofan input device, such as a capacitive sensing input device. Some morespecific examples of combined capacitive sensing are illustrated anddescribed in conjunction with an example sensor electrode pattern.Operation of the example input devices, processing system, andcomponents thereof are then further described in conjunction withdescription of an example method of combined capacitive sensing. In themethod, an absolute capacitance signal is reconstructed from acombination capacitive sensing signal.

Example Input Device

Turning now to the FIGs., FIG. 1 is a block diagram of an exemplaryinput device 100, in accordance with various embodiments. Input device100 may be configured to provide input to an electronic system/device150. As used in this document, the term “electronic system” (or“electronic device”) broadly refers to any system capable ofelectronically processing information. Some non-limiting examples ofelectronic systems include personal computers of all sizes and shapes,such as desktop computers, laptop computers, netbook computers, tablets,web browsers, e-book readers, and personal digital assistants (PDAs).Additional example electronic systems include composite input devices,such as physical keyboards that include input device 100 and separatejoysticks or key switches. Further example electronic systems includeperipherals such as data input devices (including remote controls andmice), and data output devices (including display screens and printers).Other examples include remote terminals, kiosks, and video game machines(e.g., video game consoles, portable gaming devices, and the like).Other examples include communication devices (including cellular phones,such as smart phones), and media devices (including recorders, editors,and players such as televisions, set-top boxes, music players, digitalphoto frames, and digital cameras). Additionally, the electronic systemscould be a host or a slave to the input device.

Input device 100 can be implemented as a physical part of an electronicsystem 150, or can be physically separate from electronic system 150. Asappropriate, input device 100 may communicate with parts of theelectronic system using any one or more of the following: buses,networks, and other wired or wireless interconnections. Examplesinclude, but are not limited to: Inter-Integrated Circuit (I2C), SerialPeripheral Interface (SPI), Personal System 2 (PS/2), Universal SerialBus (USB), Bluetooth®, Radio Frequency (RF), and Infrared DataAssociation (IrDA).

In FIG. 1, input device 100 is shown as a proximity sensor device (alsooften referred to as a “touchpad” or a “touch sensor device”) configuredto sense input provided by one or more input objects 140 in a sensingregion 120. Example input objects include fingers and styli (passive andactive), as shown in FIG. 1.

Sensing region 120 encompasses any space above, around, in and/or nearinput device 100, in which input device 100 is able to detect user input(e.g., user input provided by one or more input objects 140). The sizes,shapes, and locations of particular sensing regions may vary widely fromembodiment to embodiment. In some embodiments, sensing region 120extends from a surface of input device 100 in one or more directionsinto space until signal-to-noise ratios prevent sufficiently accurateobject detection. The distance to which this sensing region 120 extendsin a particular direction, in various embodiments, may be on the orderof less than a millimeter, millimeters, centimeters, or more, and mayvary significantly with the type of sensing technology used and theaccuracy desired. Thus, some embodiments sense input that includes nocontact with any surfaces of input device 100, contact with an inputsurface (e.g., a touch surface) of input device 100, contact with aninput surface of input device 100 coupled with some amount of appliedforce or pressure, and/or a combination thereof. In various embodiments,input surfaces may be provided by surfaces of casings within which thesensor electrodes reside, by face sheets applied over the sensorelectrodes or any casings, transparent lenses over a touch screendisplay, etc. In some embodiments, sensing region 120 has a rectangularshape when projected on to an input surface of input device 100.

Input device 100 may utilize any combination of sensor components andsensing technologies to detect user input in sensing region 120. Inputdevice 100 includes one or more sensing elements for detecting userinput. As a non-limiting example, input device 100 may use capacitivetechniques.

Some implementations are configured to provide images that span one,two, three, or higher dimensional spaces. Some implementations areconfigured to provide projections of input along particular axes orplanes.

In some capacitive implementations of input device 100, voltage orcurrent is applied to create an electric field. Nearby input objectscause changes in the electric field, and produce detectable changes incapacitive coupling that may be detected as changes in voltage, current,or the like.

Some capacitive implementations utilize arrays or other regular orirregular patterns of capacitive sensing elements to create electricfields. In some capacitive implementations, separate sensing elementsmay be ohmically shorted together to form larger sensor electrodes. Somecapacitive implementations utilize resistive sheets, which may beuniformly resistive.

Some capacitive implementations utilize “self capacitance” (or “absolutecapacitance”) sensing methods based on changes in the capacitivecoupling between sensor electrodes and an input object. In variousembodiments, an input object near the sensor electrodes alters theelectric field near the sensor electrodes, thus changing the measuredcapacitive coupling. In one implementation, an absolute capacitancesensing method operates by modulating sensor electrodes with respect toa reference voltage (e.g., system ground), and by detecting thecapacitive coupling between the sensor electrodes and input objects. Inone embodiment, the capacitive coupling between the sensor electrodesand input objects may be combined with the effects of the input oncoupling between sensor electrodes to estimate the total coupling of theuser to the reference voltage and/or to estimate low ground mass (LGM).

Some capacitive implementations utilize “mutual capacitance” (alsoreferred to herein as “transcapacitance”) sensing methods based onchanges in the capacitive coupling between sensor electrodes. In variousembodiments, an input object near the sensor electrodes alters theelectric field between the sensor electrodes, thus changing the measuredcapacitive coupling. In one implementation, a transcapacitive sensingmethod operates by detecting the capacitive coupling between one or moretransmitter sensor electrodes (also “transmitter electrodes” or“transmitters”) and one or more receiver sensor electrodes (also“receiver electrodes” or “receivers”). In some embodiments, atranscapacitance is measured between a transmitter electrode and areceiver that cross one another. In some embodiments, a transcapacitivemeasurement is made between a transmitter electrode and a receiverelectrode which do not cross one another. Collectively transmitters andreceivers may be referred to as sensor electrodes or sensor elements.Transmitter sensor electrodes may be modulated relative to a referencevoltage (e.g., system ground, a stationary voltage potential, or amodulated voltage signal) to transmit transmitter signals. Receiversensor electrodes may be coupled with the reference voltage tofacilitate receipt of resulting signals. A resulting signal may includeeffect(s) corresponding to one or more transmitter signals, and/or toone or more sources of environmental interference (e.g., activelymodulated pen or other electromagnetic signals). Sensor electrodes maybe dedicated transmitters or receivers, or may be configured to bothtransmit and receive. In some embodiments, one or more receiverelectrodes may be operated to receive a resulting signal when notransmitter electrodes are transmitting (e.g., the transmitters aredisabled). In this manner, the resulting signal represents noisedetected in the operating environment of sensing region 120.

In FIG. 1, a processing system 110 is shown as part of input device 100.Processing system 110 is configured to operate the hardware of inputdevice 100 to detect input in sensing region 120. Processing system 110includes parts of or all of one or more integrated circuits (ICs) and/orother circuitry components. For example, a processing system may includetransmitter circuitry configured to transmit signals with transmittersensor electrodes, and/or receiver circuitry configured to receivesignals with receiver sensor electrodes. Such transmitter circuitry mayinclude one or more analog components such as amplifiers (e.g., buffers)which are used to drive transmitter signals onto sensor electrodes. Suchreceiver circuitry may include one or more analog components such asamplifiers which are used to receive and amplify signals from the sensorelectrodes. In some embodiments, some analog components are sharedbetween transmitter circuitry and receiver circuitry. In variousembodiments, one or more analog components of the transmitter and/orreceiver circuitry may be used for both transcapacitive and absolutecapacitive sensing. In some embodiments, processing system 110 alsoincludes electronically-readable instructions, such as firmware code,software code, and/or the like. In some embodiments, componentscomposing processing system 110 are located together, such as nearsensing element(s) of input device 100. In other embodiments, componentsof processing system 110 are physically separate with one or morecomponents close to sensing element(s) of input device 100, and one ormore components elsewhere. For example, input device 100 may be aperipheral coupled to a desktop computer, and processing system 110 mayinclude software configured to run on a central processing unit of thedesktop computer and one or more ICs (perhaps with associated firmware)separate from the central processing unit. As another example, inputdevice 100 may be physically integrated in a phone, and processingsystem 110 may include circuits and firmware that are part of a mainprocessor of the phone. In some embodiments, processing system 110 isdedicated to implementing input device 100. In other embodiments,processing system 110 also performs other functions, such as operatingdisplay screens, containing a display buffer driving haptic actuators,etc.

Processing system 110 may be implemented as a set of modules that handledifferent functions of processing system 110. Each module may includecircuitry that is a part of processing system 110, firmware, software,or a combination thereof. In various embodiments, different combinationsof modules may be used. Example modules include hardware operationmodules for operating hardware such as sensor electrodes and displayscreens, data processing modules for processing data such as sensorsignals and positional information, and reporting modules for reportinginformation. Further example modules may include sensor modulesconfigured to operate sensing element(s) to detect input, determinationmodules configured to determine absolute capacitance and positions ofany inputs objects therefrom, determination modules configured todetermine changes in transcapacitance and positions of any input objectstherefrom, to combine changes in transcapacitance and absolutecapacitance to determine positions of any input objects therefrom,and/or to determine interference or actively modulated user inputs anddetermine their user input state (e.g., excessive noise, hover, contactforce, button press etc.), identification modules configured to identifygestures such as mode changing gestures, and mode changing modules forchanging operation modes.

In some embodiments, processing system 110 responds to user input (orlack of user input) in sensing region 120 directly by causing one ormore actions. Example actions include changing operation modes, as wellas GUI actions such as cursor movement, selection, menu navigation, andother functions. In some embodiments, processing system 110 providesinformation about the input (or lack of input) to some part of theelectronic system (e.g., to a central processing system of theelectronic system that is separate from processing system 110, if such aseparate central processing system exists). In some embodiments, somepart of the electronic system processes information received fromprocessing system 110 to act on user input, such as to facilitate a fullrange of actions, including mode changing actions and GUI actions.

For example, in some embodiments, processing system 110 operates thesensing element(s) of input device 100 to produce electrical signalsindicative of input (or lack of input) in sensing region 120. Processingsystem 110 may perform any appropriate amount of processing on theelectrical signals in producing the information provided to theelectronic system. For example, processing system 110 may digitizeanalog electrical signals obtained from the sensor electrodes. Asanother example, processing system 110 may perform filtering or othersignal conditioning. As yet another example, processing system 110 maysubtract or otherwise account for a baseline, such that the informationreflects a difference between the electrical signals and the baseline.As yet further examples, processing system 110 may determine positionalinformation, recognize inputs as commands, recognize handwriting, andthe like.

“Positional information” as used herein broadly encompasses absoluteposition, relative position, velocity, acceleration, and other types ofspatial information. Exemplary “zero-dimensional” positional informationincludes near/far or contact/no contact information. Exemplary“one-dimensional” positional information includes positions along anaxis. Exemplary “two-dimensional” positional information includesmotions in a plane. Exemplary “three-dimensional” positional informationincludes instantaneous or average velocities in space. Further examplesinclude other representations of spatial information. Historical dataregarding one or more types of positional information may also bedetermined and/or stored, including, for example, historical data thattracks position, motion, or instantaneous velocity over time.

In some embodiments, input device 100 is implemented with additionalinput components that are operated by processing system 110 or by someother processing system. These additional input components may provideredundant functionality for input in sensing region 120, or some otherfunctionality. FIG. 1 shows buttons 130 near sensing region 120 that canbe used to facilitate selection of items using input device 100. Othertypes of additional input components include sliders, balls, wheels,switches, and the like. Conversely, in some embodiments, input device100 may be implemented with no other input components.

In some embodiments, input device 100 may be a touch screen, and sensingregion 120 overlaps at least part of an active area of a display screen.For example, input device 100 may include substantially transparent(including but not limited to opaque metal meshes) sensor electrodesoverlaying the display screen and provide a touch screen interface forthe associated electronic system 150. A metal mesh over a display may bedesigned to minimize visible Moire’ patterns with the subpixel patternsbelow, and to minimize reflection of light from above. In one embodimentthe mesh may be patterned to substantially surround each subpixel whileallowing sufficient (e.g. greater than +/−75 degree) and patterned tosegment the electrodes (e.g. into orthogonal X and Y axis diamondelectrodes). The display screen may be any type of dynamic displaycapable of displaying a visual interface to a user, and may include anytype of light emitting diode (LED), organic LED (OLED), cathode ray tube(CRT), liquid crystal display (LCD), plasma, electroluminescence (EL),or other display technology. Input device 100 and the display screen mayshare physical elements. For example, some embodiments may utilize someof the same electrical components for displaying and sensing. As anotherexample, the display screen may be operated in part or in total byprocessing system 110.

It should be understood that while many embodiments are described in thecontext of a fully functioning apparatus, the mechanisms are capable ofbeing distributed as a program product (e.g., software) in a variety offorms. For example, the mechanisms that are described may be implementedand distributed as a software program on information bearing media thatare readable by electronic processors (e.g., non-transitorycomputer-readable and/or recordable/writable information bearing mediareadable by processing system 110). Additionally, the embodiments applyequally regardless of the particular type of medium used to carry outthe distribution. Examples of non-transitory, electronically readablemedia include various discs, memory sticks, memory cards, memorymodules, and the like. Electronically readable media may be based onflash, optical, magnetic, holographic, or any other tangible storagetechnology.

FIG. 2A shows a portion of an example sensor electrode pattern 200 whichmay be utilized in a sensor to generate all or part of the sensingregion of input device 100, according to various embodiments. Inputdevice 100 is configured as a capacitive sensing input device whenutilized with a capacitive sensor electrode pattern. For purposes ofclarity of illustration and description, a non-limiting simplerectangular sensor electrode pattern 200 with a first plurality ofsensor electrodes X and a second plurality of sensor electrodes Y isillustrated. Although the labels X and Y are utilized and FIG. 2Aillustrates that the X and Y sensor electrode subsets are substantiallyorthogonal to one another, an orthogonal relationship between thecrossing first and second subsets of sensor electrodes is not required.In one embodiment, the sensor electrodes X and Y may be arranged ondifferent sides of the same substrate. For example, each of the firstplurality X and second plurality of sensor electrode may be disposed onone of the surfaces of a substrate. In one such an embodiment, sensorelectrodes X are disposed on a first side of a substrate, while sensorelectrodes Y are disposed on an opposing side of the substrate. In otherembodiments, the sensor electrodes may be arranged on differentsubstrates. For example, each of the each of the first and secondplurality of sensor electrode(s) may be disposed on surfaces of separatesubstrates which may be adhered together. In another embodiment, thesensor electrodes are all located on the same side or surface of acommon substrate. In one example, a first plurality of the sensorelectrodes include jumpers in regions where the first plurality ofsensor electrodes crossover the second plurality of sensor electrodes,where the jumpers are insulated from the second plurality of sensorelectrodes. In one or more embodiments, the sensor electrodes mayinclude at least one display electrode configured for display updatingand capacitive sensing. The display electrode may be selected from alist including, but not limited to, a segment of a segmented Vcomelectrode, a source electrode, a gate electrode, a cathode electrode,and an anode electrode.

The first plurality of sensor electrodes may extend in a firstdirection, and the second plurality of sensor electrodes may extend in asecond direction. The second direction may be similar to or differentfrom the first direction. For example, the second direction may beparallel with, perpendicular to, or diagonal to the first direction.Further, the sensor electrodes may each have the same size or shape ordiffering size and shapes. In one embodiment, the first plurality ofsensor electrodes may be larger (larger surface area) than the secondplurality of sensor electrodes. In other embodiments, the firstplurality and second plurality of sensor electrodes may have a similarsize and/or shape. Thus, the size and/or shape of the one or more of thesensor electrodes may be different than the size and/or shape of anotherone or more of the sensor electrodes. Nonetheless, each of the sensorelectrodes may be formed into any desired shape on their respectivesubstrates.

In other embodiments, one or more of sensor electrodes are disposed onthe same side or surface of the common substrate and are isolated fromeach other in the sensing region 120.

FIG. 2B illustrates an example matrix array of sensor electrodes,according to various embodiments. As illustrated in FIG. 2B, the sensorelectrodes 210 may be disposed in a matrix array where each sensorelectrode may be referred to as a matrix sensor electrode. In oneembodiment, each sensor electrode of sensor electrodes is substantiallysimilar size and/or shape. In one embodiment, one or more of sensorelectrodes of the matrix array of sensor electrodes may vary in at leastone of size and shape. Each sensor electrode of the matrix array maycorrespond to a pixel of a capacitive image. Further, two or more sensorelectrodes of the matrix array may correspond to a pixel of a capacitiveimage. In various embodiments, each sensor electrode of the matrix arraymay be coupled a separate capacitive routing trace of a plurality ofcapacitive routing traces. In various embodiments, the sensor electrodes210 include one or more grid electrodes disposed between at least twosensor electrodes of sensor electrodes. The grid electrode and at leastone sensor electrode may be disposed on a common side of a substrate,different sides of a common substrate and/or on different substrates. Inone or more embodiments, the sensor electrodes and the grid electrode(s)may encompass an entire voltage electrode of a display device. Thevoltage electrode may be selected from a list including, but not limitedto, a Vcom electrode, a segment of a segmented Vcom electrode, a sourceelectrode, a gate electrode, a cathode electrode, and an anodeelectrode. Although the sensor electrodes may be electrically isolatedon the substrate, the electrodes may be coupled together outside of thesensing region 120—e.g., in a connection region. In one embodiment, afloating electrode may be disposed between the grid electrode and thesensor electrodes. In one particular embodiment, the floating electrode,the grid electrode and the sensor electrode include the entirety of acommon electrode of a display device. Each sensor electrode may beindividually coupled to the processing system or coupled to theprocessing system through one or more multiplexers or switchingmechanisms.

The illustrated sensor electrode pattern in FIG. 2A is made up of aplurality of sensor electrodes X (X1, X2, X3, X4) which may be used asboth transmitter electrodes and receiver electrodes and a plurality ofsensor electrodes Y (Y1, Y2, Y3, Y5) which may be used as bothtransmitter electrodes and receiver electrodes. Sensor electrodes X andY overlay one another in an orthogonal arrangement, in this example. Itis appreciated that in a crossing sensor electrode pattern, such as theillustrated example of FIG. 2A, some form of insulating material orsubstrate is typically disposed between sensor electrodes Y and X. Forpurposes of clarity, depictions of these substrates and insulators havebeen omitted herein.

In the illustrated example of FIG. 2A, capacitive pixels may be measuredvia transcapacitive sensing. For example, capacitive pixels may belocated at regions where transmitter and receiver electrodes interact.The pixels may have a variety of shapes, depending on the nature of theinteraction. In the illustrated example, capacitive pixels are locatedwhere transmitter and receiver electrodes overlap one another.Capacitive coupling 290 illustrates one of the capacitive couplingsgenerated by sensor electrode pattern 200 during transcapacitive sensingwith sensor electrode Y5 as a transmitter electrode and sensor electrodeX4 as a receiver electrode or with sensor electrode X4 as a transmitterelectrode and sensor electrode Y5 as a receiver electrode. Capacitivecoupling 295 illustrates one of the capacitive couplings generated bysensor electrode pattern 200 during transcapacitive sensing with sensorelectrode Y5 as a transmitter electrode and sensor electrode Y4 as areceiver electrode or with sensor electrode Y4 as a transmitterelectrode and sensor electrode Y5 as a receiver electrode. Capacitivecoupling 297 illustrates one of the capacitive couplings generated bysensor electrode pattern 200 during transcapacitive sensing with sensorelectrode X4 as a transmitter electrode and sensor electrode Y3 as areceiver electrode or with sensor electrode X3 as a transmitterelectrode and sensor electrode X4 as a receiver electrode. Whenaccomplishing transcapacitive measurements, the capacitive couplings,are areas of localized capacitive coupling between sensor electrodes.The capacitive coupling between sensor electrodes change with theproximity and motion of input objects in the sensing region associatedwith sensor electrodes. In some instances, areas of capacitive couplingsuch as 290, 295, and 297 may be referred to as capacitive pixels. Itshould be noted that the different types of capacitive couplings 290,295, 297 have different shapes, sizes, and or orientations from oneanother due to the particular nature of the interactions. As anotherexample, absolute capacitive couplings may increase where the area ofoverlap between a sensor electrode and a user input depending on theseries coupling of the user through a voltage reference (e.g., systemground) from which the respective receiver is modulated. As one example,dashed box 299 represents an area of absolute capacitive coupling whichmay be associated with sensor electrode X1; other sensor electrodessimilar have areas of absolute capacitive coupling. As a furtherexample, the absolute capacitive series couplings may also include theeffect of user coupling to other transmitter electrodes in parallel tothe coupling to the reference voltage.

In the illustrated example of FIG. 2B, capacitive pixels may be measuredvia transcapacitive sensing. For example, capacitive pixels may belocated at regions where transmitter and receiver electrodes interact.In the illustrated example, capacitive pixels are located wheretransmitter and receiver electrodes are coupled to one another. Forexample, capacitive coupling 280 illustrates one of the capacitivecouplings generated by sensor electrode pattern 210 duringtranscapacitive sensing with sensor electrode SE1 as a transmitterelectrode and sensor electrode SE2 as a receiver electrode or withsensor electrode SE1 as a transmitter electrode and sensor electrode SE2as a receiver electrode. Capacitive coupling 281 illustrates one of thecapacitive couplings generated by sensor electrode pattern 210 duringtranscapacitive sensing with sensor electrode SE1 as a transmitterelectrode and sensor electrode SE3 as a receiver electrode or withsensor electrode SE3 as a transmitter electrode and sensor electrode SE1as a receiver electrode. Capacitive coupling 282 illustrates one of thecapacitive couplings generated by sensor electrode pattern 210 duringtranscapacitive sensing with sensor electrode SE1 as a transmitterelectrode and sensor electrode SE4 as a receiver electrode or withsensor electrode SE4 as a transmitter electrode and sensor electrode SE1as a receiver electrode. When accomplishing transcapacitivemeasurements, the capacitive couplings, are areas of localizedcapacitive coupling between sensor electrodes. The capacitive couplingbetween sensor electrodes changes with the proximity and motion of inputobjects in the sensing region associated with sensor electrodes. As oneexample, dashed box 284 represents an area of absolute capacitivecoupling which may be associated with sensor electrode SE4; other sensorelectrodes in sensor electrode pattern 210 similar have areas ofabsolute capacitive coupling. The absolute capacitance of any one ormore of the sensor electrodes in sensor electrode pattern 210 may alsobe measured.

For purposes of brevity and clarity, the embodiments discussed in FIGS.3A, 3B, 4, 5, 6A, 6B, 6C, 6D, 7A, 7B, 7C, 7D, 7A, 7B, 7C, 7D, 7E, 7F,and 7G are described using the example sensor electrode pattern 200 ofFIG. 2A. It should be appreciated by one of skill in the art that theembodiments described in FIGS. 3A, 3B, 4, 5, 6A, 6B, 6C, 6D, 7A, 7B, 7C,7D, 7A, 7B, 7C, 7D, 7E, 7F, and 7G can similarly be implemented using avariety of other sensor electrode patterns, including sensor electrodepattern 210 of FIG. 2B.

In some embodiments, sensor electrode pattern 200 is “scanned” todetermine these capacitive couplings. That is, the transmitterelectrodes are driven to transmit transmitter signals. Transmitters maybe operated such that one transmitter electrode transmits at one time,or multiple transmitter electrodes transmit at the same time. Wheremultiple transmitter electrodes transmit simultaneously, these multipletransmitter electrodes may transmit the same transmitter signal andproduce an effectively larger transmitter electrode, or these multipletransmitter electrodes may transmit different transmitter signals. Forexample, multiple transmitter electrodes may transmit differenttransmitter signals according to one or more coding schemes that enabletheir combined effects on the resulting signals of receiver electrodesto be independently determined based on the multiple results of multipleindependent codes. In one embodiment, a first sensor electrode may bedriven with a first transmitter signal based on a first code of aplurality of distinct digital codes and a second sensor electrode may bedriven with a second transmitter signal based on a second code of theplurality of distinct digital codes, where the first code may beorthogonal to the second code. With regard to FIG. 2B, the sensorelectrodes may be driven and received with such that at least two sensorelectrodes may be simultaneously driven. In one or more embodiments,each of the sensor electrodes may be simultaneously driven. In such anembodiment, each sensor electrode may be driven with a transmittersignal based on a different one of a plurality of orthogonal digitalcodes. Further, the sensor electrodes may be driven such that a first atleast one sensor electrode is driven differently that a second at leastsensor electrode. In one or more embodiments, the sensor electrodes aredriven such that along each row and column alternating sensor electrodesare driven differently.

The receiver electrodes may be operated singly or in multiples toacquire resulting signals. The resulting signals may be used todetermine measurements of the capacitive couplings at the capacitivepixels. Note that the receiver signals may also be multiplexed such thatmultiple electrodes may be measured with a single receiver (e.g., analogfront end or “AFE”). Furthermore, the receiver multiplexer may beimplemented such that the receiver is simultaneously coupled to andsimultaneously receives resulting signals from multiple sensorelectrodes. In such implementations, the resulting signals include codedresults from the multiple sensor electrodes. Note in variousembodiments, that multiple “absolute capacitance” electrodes may bedriven simultaneously with the same modulation relative to a referencevoltage and such that they are guarding each other, or some may bedriven relative to each other modulated relative to a system referencevoltage such that they measure both a transcapacitive and an absolutecapacitive signal simultaneously.

A set of measurements from the capacitive couplings or pixels form a“capacitive image” (also “capacitive frame”) representative of thetranscapacitive couplings a. For example a capacitive image may be madeup of a set of capacitive pixels, such as capacitive coupling 290.Multiple capacitive images may be acquired over multiple time periods,and differences between them used to derive information about input inthe sensing region. For example, successive capacitive images acquiredover successive periods of time can be used to track the motion(s) ofone or more input objects entering, exiting, and within the sensingregion. Also, in various embodiments, a “capacitive image” may be formedby absolute capacitive measurements of a matrix array of sensorelectrodes (e.g., sensor electrode pattern 210 of FIG. 2B). In suchembodiments, sensor electrodes may be operated for absolute capacitivesensing depending on the multiplexer settings. For example the sensorelectrodes may be grouped in to rows, columns and/or other combinationsof sensor electrodes.

A set of measurements from the capacitive coupling/pixels along one axismay be taken to form a “transcapacitive profile” (also “profile frame”)representative of the capacitive couplings at the capacitivecouplings/pixels between parallel electrodes on an axis (e.g.,electrodes X or Y). For example a transcapacitive profile may be made upfrom a set of horizontal capacitive pixels, such as capacitivecoupling/pixel 295, or from a set of vertical pixels, such as capacitivecoupling/pixel 297. Multiple transcapacitive profiles along one or moreaxes may be acquired over multiple time periods, and differences betweenthem used to derive information about input in the sensing region. Forexample, successive transcapacitive profiles acquired over successiveperiods of time for an axis can be used to track the motion(s) of one ormore input objects entering, exiting, and within the sensing region.Alternately, a set of measurements from the capacitive coupling along anaxis may be taken from an “absolute capacitive profile” (also called“ABS profile”) representative of the capacitive couplings between theparallel electrodes on an axis and the series capacitance from the userinput through the coupling to the reference electrode which the absolutereceivers are modulated.

In some embodiments, one or more sensor electrodes Y or X may beoperated to perform absolute capacitive sensing at a particular instanceof time. For example, sensor electrode X1 may be charged by driving amodulated signal onto sensor electrode X1, and then the capacitance ofreceiver electrode X1 to system reference voltage including the couplingthrough the user input may be measured. In such an embodiment, an inputobject 140 interacting with sensor electrode X1 alters the electricfield near sensor electrode X1, thus changing the measured capacitivecoupling. In this same manner, a plurality of sensor electrodes X and/orsensor electrodes Y may be used to measure absolute capacitance atdifferent times or at times that overlap partially or completely.

As will be described herein, in some embodiments, combined sensing canbe performed by driving a sensing signal onto a sensor electrode (e.g.,sensor electrode X1) for the purposes of measuring absolute capacitancewith that sensor electrode and, simultaneously with the driving of thatsensor electrode, other sensor electrodes that cross and do not crossthat sensor electrode (e.g., sensor electrodes Y that cross sensorelectrode X1 and one or more other sensor electrodes X which do notcross sensor electrode X1) may be used as receivers to obtaintranscapacitive measurements between themselves and the driven sensorelectrode.

FIG. 3A shows a more detailed block diagram of the input device 100 ofFIG. 1, according to an embodiment. By way of example and not oflimitation, FIG. 3A depicts and describes a crossing sensor electrodepattern as shown in FIG. 2A; however, it should be appreciated that thedescription and techniques presented with respect to FIG. 3A maysimilarly be applied to the sensor electrode pattern 210 of FIG. 2B. InFIG. 3A capacitive sensing input device 100, in the illustratedembodiment, includes sensor electrodes of sensor electrode pattern 200.It should be appreciated that for purposes of clarity some componentssuch as substrates, insulating material, and routing traces are omittedso as not to obscure the depicted portions. Sensor electrodes X and Y orsensor electrode pattern 200 are shown coupled by routing traces toprocessing system 110. For example, routing traces 310 couple sensorelectrodes Y1, Y2, Y3, Y4, and Y5 with processing system 110, androuting traces 320 couple sensor electrodes X1, X2, X3, and X4 withprocessing system 110. Sensor electrode pattern 200 is disposed above aconductive system electrode G. The system electrode may be driven with asystem reference, which may also be referred to as a system ground. Inone or more embodiments, the system electrode G may be part of thehousing of the input device, or the battery of the input device. In oneor more embodiments an optional electrode B (depicted in FIG. 3B but notin FIG. 3A) may be disposed between the sensor electrodes and systemground electrode. Electrode B may be driven with a shielding signal,which may be a substantially constant voltage or a varying voltage(i.e., guard signal).

Electrode S1 overlaps at least a portion of routing traces 310, and maybe used to shield signals on these routing traces. Electrode S1 iscoupled with processing system 110 by routing trace 311 and may be heldat a constant voltage potential or modulated by processing system 110.An electrode S2 overlaps at least a portion of routing traces 320, andmay be used to shield signals on these routing traces. Electrode S2 iscoupled with processing system 110 by routing trace 321 and may be heldat a constant voltage potential or modulated by processing system 110.As illustrated, in some embodiments, input device 100 is communicativelycoupled with electronic system 150. In one embodiment, the constantvoltage potential may be the system reference. In other embodiments, theconstant voltage potential may be any substantially constant voltage.

In one embodiment, change in the position of an input object, such asfinger F1, may also change the capacitances C_(Y5X1) or C_(Y5X3).Moreover, another input object, such as finger F2, may be further awayfrom the sensor electrodes than finger F1 and may have no or veryminimal substantially effect on C_(X3F2), C_(X4F2), and C_(X4F2).

In FIG. 3A, Arrows A, represent the location and direction of a frontside-sectional view that is illustrated in FIG. 3B. Additionally, inFIG. 3A, circle F1 represents the interaction area of a finger, F1, thatis illustrated in FIG. 3B; while circle F2 represents the interactionare of a finger, F2, that is also illustrated in FIG. 3B.

FIG. 3B shows an exploded side sectional view A-A of a portion of theinput device of FIG. 3A, according to an embodiment. As with FIG. 3A,portions such as substrates, insulators, and routing traces have beenomitted for the purposes of clarity so as not to obscure the depictedportions. In the illustrated embodiment, it can be seen that electrodeS1 is disposed in the same layer as sensor electrodes X, and electrodeS2 is disposed in the same layer as sensor electrodes Y. In otherembodiments, sensor electrodes S1 and S2 may be disposed in the samelayer as one another or in different layers than depicted; for example,electrode S2 may be disposed above routing traces 320 rather than belowas depicted, and sensor electrode S1 may be disposed below routingtraces 310 rather than above as depicted. In addition to section A-A,two input objects 140 in the form of a first finger, F1, and a secondfinger, F2, are shown along with a variety of capacitive couplingswithin and to the sensor electrodes X and Y of sensor electrode pattern200.

With an array of sensing electrodes, such as sensor electrode pattern200, which are arranged in a crossing array where two sets of sensorelectrodes (sensor electrodes X and sensor electrodes Y) are roughlyparallel within the set, the sets may effectively couple together in aset of capacitive combinations larger than that within either setseparately (e.g., the electrode sets may be roughly perpendicularbetween them). Consider an example where there are M sensor electrodesin the set of X sensor electrodes and N sensor electrodes in the set ofY electrodes. Where the sets of X and Y sensor electrodes are roughlyorthogonal, in areas where they extend to cover each other there will becapacitances described by transcapacitance between the sets (e.g.,C_(X1Y2) and C_(Y2X1) for a total number of crossings of up to 2*(M*N)).There will also be capacitances described by absolute capacitance up toM+N=P) from each of the electrodes to a chassis ground (e.g., C_(X1X1)or C_(Y2Y2)). Further within the sets there will be capacitancesdescribed by transcapacitance, which are within the parallel sets (e.g.,up to M*(M−1) and N*(N−1) additional capacitances like C_(X1X2) andC_(YLY2)).

In general, the number of set-to-set transcapacitances, intra-settranscapacitances, and absolute capacitances, will be a matrix of allcapacitances between each of the sets of electrodes (e.g., P²=[M+N]²).There may also be other electrodes including relatively stationary (tosystem ground) shields, or modulated electrodes (e.g., guards) which mayminimize uncontrolled capacitive coupling, or others that may interfererandomly or by increasing the required dynamic range of capacitivemeasurement. In various embodiments, the number of capacitances varybased on the sensor electrode pattern, and in various embodiments, thesensor electrode pattern may be configured to provide a predeterminednumber of absolute, set-to-set transcapacitances and/or intra-settranscapacitances. For example, with reference to the sensor electrodepattern shown in FIG. 2B, (N*M)² capacitances may be determined, where Nis the number of sensor electrodes disposed along a first axis (e.g.,along X axis) and M is the number of sensor electrodes disposed along asecond axis (e.g., along Y axis).

The chassis of input device 100 may in turn be coupled to free-spaceand/or to one or more conductive input objects. Those objects may beeffectively AC grounded (to the chassis) either by contact or throughfree-space, or they may be effectively “floating.” Further high(relative to vacuum or air) dielectric objects may also exist and changecapacitive couplings of the array of sensor electrodes in sensorelectrode pattern 200. For example, the sensitivity of the capacitivemeasurement of the transcapacitances and the cross coupling ofcapacitances may be reduced (shielded) or increased (coupled through thesensor electrode) respectively when the capacitive coupling of thechassis with the input object is high or low respectively. In particularthis may tend to make simple measurements of the capacitances moredifficult in some instances when conventional measurement techniques areemployed.

As previously described, the array of sensor electrodes in sensorelectrode pattern 200 may include transmitters and receivers, where mostgenerically each of the sensor electrodes may be a transmitter(modulated relative to system ground), a receiver which measures charge(or modulated currents) coupled through the capacitances of transmittersmodulated relative to them (e.g., stationary in voltage relative to thechassis ground), or both (e.g., an absolute capacitance sensitivereceiver modulated relative to ground which measures that capacitanceand also any other relatively modulated electrodes). The sensorelectrodes may also be decoupled from low impedance outputs/inputs suchthat their other couplings dominate and coupling between occur (e.g.,reduced shielding/guarding). The capacitances in sensor electrodepattern 200 may then be estimated by measuring the charge to voltageratio (e.g., measuring charge for a fixed voltage modulation, ormeasuring voltage for a fixed charge modulation). In some embodiments,when the coupling from an input object to system ground is low, thedirect coupling between sensor electrodes can increase (e.g., theintra-set transcapacitance may increase or the increased couplingthrough the input object may be comparable to the reduced directcoupling between sets). In such embodiments, changes to the electricfield due to the input object may be low. This makes conventionalestimations of the capacitances (e.g., C_(X1Y1) and C_(X4Y2)) based onsingle measurements of charge versus voltage inaccurate and in someembodiments, it may be indeterminable. However, by correlating multiplemeasurements, independent estimates of direct coupling capacitances(e.g., similar to those where the input is fully grounded) can be madeand input locations based on those corrected estimates.

For example, combined capacitive sensing can be employed by scanningwhen all electrodes are receivers (e.g., modulating each electrode insequence while receiving on the others) will generate a P*P matrix (ofmeasured capacitance or demodulated charge) where the total number ofelectrodes is P=M+N. In the P*P matrix there are two set-to-setcapacitive images (since each symmetric capacitance is measured twice,e.g., C_(X1Y4) and C_(Y4X1)) so two reports may be generated when all ofthe electrodes are scanned. Such inter-set capacitive images may also bereferred to as transcapacitive images as they are made up oftranscapacitive measurements. There are also two pairs of otherintra-set transcapacitance profiles (M×M and N×N respectively) and twoabsolute capacitance profiles (a vector of M and a vector of N). In thecase where user input coupling to system ground is known, correctionscan be made to the images. However, it is possible for multiple levelsof input coupling to be present (e.g., a “floating” coin and a groundedfinger) simultaneously. This makes the location of the objects and theirintroduction and removal difficult to distinguish with a single,conventional measurement of transcapacitance at each crossover location.However, by correlating various capacitance measurements the degree ofcoupling can be estimated and in various embodiments, it can be locallyestimated.

Note that, when performing combined capacitive sensing, the differentmeasurements of both the same symmetric capacitance (though measured ata different time) or of different types of capacitance (e.g., absolutecapacitance, set-to-set transcapacitance, and intra-settranscapacitance) may be correlated with each other to better interpretthe input signals (e.g., even when they are changing or when the groundcoupling of the user is low).

With reference to FIGS. 3A and 3B, the charges transferred by thedifferent capacitances (e.g., absolute capacitances such as C_(X1F1),C_(X3F2), C_(X4F2), C_(Y5F1), C_(Y5F2); set-to-set transcapacitancesC_(Y5X1), C_(Y5X2), C_(Y5X3), C_(Y5X4); and intra-set transcapacitancessuch as C_(X1X2), C_(X2X3)) all occur at substantially the same timealong with other capacitances (e.g., C_(F1S1), C_(FG), and C_(F2B)) butthe coupling through input objects can confound the normal (e.g.,well-grounded user input) assumptions about their effect simply ontranscapacitances collected according conventional sensing techniques.This can lead to bad baselines and Low Ground Mass (LGM) effects thatare difficult to disambiguate from moisture or multiple input objectswhen conventional capacitive sensing techniques are employed. However,when using combined capacitive sensing techniques described herein thecoupling of an input object to ground can be determined by either thereduced charge coupling of an object on an absolute profile measurementor by the increased charge coupling on a transcapacitance measurement ora combination of both.

FIG. 4 shows a matrix 400 of capacitances associated with the inputdevice illustrated in FIG. 3A, according to an embodiment. The multiplecapacitances illustrated in matrix 400 may be acquired via techniques ofcombined capacitive sensing, in some embodiments. For example, absolutecapacitances such as C_(X1X1) . . . C_(X4Y4) form an X profile; absolutecapacitances such as C_(Y1Y1) . . . C_(Y5Y5) form a Y profile;set-to-set transcapacitances such as C_(X1Y1) form an X to Y capacitiveimage; set-to-set transcapacitances such as C_(Y1X1) form an Y to Xcapacitive image; intra-set transcapacitances such as C_(X1X2) andC_(X2X1) form an X to X transcapacitive profile; intra-settranscapacitances such as C_(Y1Y2) and C_(Y2Y1) form a Y to Ytranscapacitive profile; and other capacitances to the shields, guards,and system ground electrode G, such as C_(F1S1) and C_(FG), round outthe matrix. In various embodiments, a first sensor electrode ismodulated such that its absolute capacitance to ground is measured atthe same time that the transcapacitive coupling between the first sensorelectrode and proximate sensor electrodes is measured. For example,sensor electrode X₁ may be modulated to measure its absolute capacitanceC_(X1F1) and to measure the transcapacitive couplings C_(X1Y1),C_(X1Y5), C_(X1X2) and C_(X1X3).

Indeed, various capacitive changes may be correlated differentlydepending on how well input object(s) is/are coupled to system ground.For example, relatively uncoupled inputs (e.g., from different users)can be separately identified by their intra-set transcapacitivecapacitance matrices. In such an example, a first user may be holdingthe input device while a second user is not; however, other orientationsare also possible. The intra-set transcapacitive capacitance effectsbetween separated electrodes is usually also very small so that even inan unknown startup condition a large intra-set transcapacitance betweenseparated sensor electrodes almost certainly indicates a floatingconductive object (e.g., moisture, a coin, etc.) that might be ignoredand that its effect (e.g., on delta set-to-set transcapacitive) could beignored when it is removed as well. Alternatively, an effect may beestimated and the estimate removed from data that is reported to a hostprocessor and/or used to calculate reported user inputs. Note thatscanning speed to reconstruct the relevant capacitances is taken intoaccount through modeling; this is because any motion of an input objectmay change the correlated capacitances unless the motion of the inputobjects is modeled. In some embodiments, interleaved measurements of thecapacitances when scanning may aid in reducing such “motion artifacts.”

When using the techniques of combined capacitive sensing (describedherein) to capture capacitances, the LGM effect can typically be modeledby a set of four capacitances from each input object to the sensor(C_(X1F1), C_(Y1F1), C_(X1Y1), and C_(FG)) at each pixel/capacitivecoupling that the input object covers. Most input objects are wellcoupled together (e.g., humans have ˜150 pF to free space and −75 pFseries coupling to each other which easily dominate most othercapacitive couplings to a sensor) so that the capacitance from a fingerto ground (C_(FG)) may often be treated as a single variable mostlyindependent of the number of simultaneous input objects and nearbytranscapacitive pixels/capacitive couplings (e.g., crossovers betweenelectrode sets that are located on a neighboring electrode). Multi-input(e.g., multi-touch) interfaces with an input device are more complex,but these may still be modeled by additional capacitances (e.g.,C_(X4F1), C_(X1F1), C_(Y5F1), C_(Y5F2), C_(X4Y5)). It is useful tomeasure at least one of the intra-set transcapacitances (e.g., C_(X1X4)and C_(Y5Y1)) in addition to the absolute capacitances such that crosscapacitive effects can be detected independently and corrected. Notethat for each user input there are three changes in capacitance whichare of great interest (the delta capacitance from the X electrodes tothe finger, dC_(XF); the delta capacitance from the Y electrodes to thefinger, dC_(YF); and the delta capacitance from a transmitting sensorelectrode to a receiving sensor electrode, dC_(TR)) for each inputcapacitive pixel and one uncontrolled capacitance C_(FG) associated withthe coupling of an input object to the chassis. It should be noted thateach additional input capacitive pixel coupling adds three more of thesecapacitances of interest.

The charge coupling that can be measured (e.g., by a capacitive sensorarray such as sensor electrode pattern 200) includes up to 5 capacitivemeasurements if multiple pixels are covered. Also for a particularsensor design the ratio of C_(XF) and C_(YF) to C_(XY) can be correlatedwith a particular C_(FG) and/or coupling between inputs (e.g., for afully covered capacitive pixel, with a given electrode configurationthere is an expected ratio between dC_(XY), dC_(XF), and dC_(YF) for agiven C_(FG)). Using such correlations between capacitive measurementsimages of C_(YS) and profiles of C_(XF) and C_(YF) can be reconstructed(e.g., errors due to C_(FG) may be estimated and/or corrected for) in away that is roughly independent of C_(FG) (e.g., as if it the input iseffectively grounded), and/or each input object may be classified by itschassis coupling (e.g., as a floating or grounded object). It is oftenpreferred that “un-grounded” objects are ignored (e.g., water droplets,or coins) while even partially grounded objects (e.g., small fingers)are accurately detected even when they are only partially coupled to thechassis of the sensor. Although, in some embodiments, sensor electrode Bmay be modulated to estimate the capacitive coupling between sensorelectrode B and system ground.

One method of detecting each of the capacitances within the full Pmatrix is “one hot” scanning where each of the sensor electrodes ismodulated in sequence while the others are held relatively stationary(such as at ground, or some fixed or commonly modulated voltagepotential). In one implementation the modulated sensor electrodeabsolute/self capacitance (e.g., coupling to the chassis) may besimultaneously measured such that all electrodes are used as receivers.In this way part, or the entire matrix of capacitances may be measuredor scanned independently (although the charge coupling through C_(FG)may require multiple measurements from separate pixels or somecorrelation dependent on sensor design). In various embodiments, eachsensor electrode that is scanned measures one row of array matrix 400 ofFIG. 4 while each column represents the measurement by a sensorelectrode. By measuring the transcapacitance matrix by scanningelectrodes in sequence from the crossing set of electrodes the reducedcharge coupling seen when multiple (or long and narrow) objects areplaced on a single transmitting electrode since an orthogonal set ofelectrodes will only overlap the long object at a single location.

In some embodiments, different sensing schemes other than “one hot”scanning can be done to increase the power in various measurements,reduce interference and/or and increase the acquisition rate. Forincreased signal and interference tolerance each sensor may be modulatedas often as possible, in some embodiments. There are possible dynamicrange issues if the coupling between adjacent or overlapping sensorelectrodes is particularly high, but there may also be opportunities toreduce the charge coupled dynamic range. For example, in someembodiments, some sensor electrodes such as sensor electrodes Y may belonger and or wider, and thus these sensor electrodes may have more CGback coupled ground capacitance, which limits their dynamic range. Insuch a case, neighboring electrodes (e.g., X₁ and X₃) may not bemeasured when X₂ is modulated relative to them. Similarly, in someembodiments, some sensor electrodes such as sensor electrodes X may beshorter and/or narrower, and may be driven to “guard” the others of thesensor electrodes X that are used for transmitting. In variousembodiments, only a subset of the simultaneous capacitive measurementsmay be acquired by the processing system. In such embodiments,processing system may only use those sensor electrodes configured toprovide the least dynamic range. For example measured receiverelectrodes may be narrower or shorter than modulated transmitter orguarding electrodes, and the receiver electrodes may be spaced (due totheir narrowness) at a larger distance to each other. Further, theguarding electrodes may be disposed between the receiver sensorelectrode to reduce their intra group transcapacitive coupling dynamicrange. In some embodiments, some sensor electrodes that transmit canfurther reduce the required dynamic range by transitioning farther thanthe other sensor electrodes (e.g., by being driven with a modulatedsignal having greater amplitude but being in phase with) and thussubtracting charge that would otherwise need to be supplied by thereceivers that are coupled with receiver sensor electrodes to maintainthe voltage relative to system ground when the transmitter electrode ismodulated. In other embodiments, coded sequences which minimize dynamicrange while optimizing independence of measurements and sensing SNR maybe used.

Both (or only one) of the sensor electrodes X and the sensor electrodesY can still be measuring absolute capacitance profiles whiletransmitting or receiving. In one embodiment, Y may be the preferredshorter and/or narrower and more widely spaced electrodes with X fillingspace between. For scanning, one or more of the sensor electrodes Y cantransition the opposite direction (e.g., 180 degrees out of phase). Byswinging in opposite direction from the electrodes X, this increases thevoltage difference between the orthogonal sensor electrode sets and thusthe Signal to Noise Ratio (SNR) and interference performance ofset-to-set transcapacitance, as well as the interference performance ofany intra-set transcapacitance measurements within either set. Note, insome embodiments, that if all of the sensor electrodes but the scanningsensor electrode are modulated together they may be measuring absolutecapacitance and guarding all other similarly driven electrodes, whileonly the single scanning electrode may be used to measuretranscapacitance between sensor electrodes. Multiple sensor electrodescan also be driven in coded sequences to improve SNR. Where absolutemeasurements are mixed with the result of other measurements may beinterleaved to reduce the effect of temporal variation.

In one embodiment, all of the sensor electrodes in a sensor electrodearray (e.g., sensor electrode pattern) are modulated in phase. Invarious embodiments, the amplitudes may vary between axes for thepreviously mentioned charge subtraction effects to balance the requireddynamic range required of the different chassis couplings of X and Ysensor electrode sets). This allows a measurement of the P absolutecapacitive measurements (mixed with some transcapacitance if they arenot modulated with the same amplitude). This can facilitate detectinginputs at longer distances with lower power for “proximity” and “doze”modes. Then, while almost all of the electrodes are still modulated inphase, a single sensor electrode (or a single sensor electrode on eachaxis) may be modulated in the opposite phase to independently measurethe set-to-set transcapacitive matrix (M*N) and the intra-settranscapacitive capacitive matrix (e.g., M*M or N*N). In one embodiment,neighboring intra-set transcapacitively coupled sensor electrodes mayhave reduced modulation (e.g., stationary voltage relative to systemground) to reduce the required dynamic range. Once all of the sensorelectrodes significantly affected by user input are modulated, enoughmeasurements of charge coupling have been made to distinguish andindependently reconstruct grounded, partially grounded, and effectivelyun-grounded conductive (or high dielectric) objects influencing theinput device. These reconstructed images, profiles, and distinguishedinput types may be used to control user input (e.g., on a touch screenuser interface/operating system).

Furthermore, capturing active pen signals (e.g., another transmitteroutside the sensor array) can be done in half the time or with half thebandwidth when both axes of sensor electrodes (e.g., sensor electrodes Xand sensor electrodes Y) are sensing simultaneously since both profilescan be captured simultaneously. If multiple independent measurements ofthese profiles are made, then the active input can be furtherdistinguished from the other two types. In this way an additional typeof input can be measured substantially simultaneously.

For low voltage high dynamic range receivers, in some embodiments, a“current conveyor” technique may be used to translate the receivedcharge from a receiving sensor electrode. In order to measureabsolute/self capacitance a sensor electrode is modulated between atleast two voltages. Doing this with a single circuit configuration mayimpose restrictions on the size of the voltage change (e.g., how closeto a particular high or low voltage rail) due to the type of transistor(e.g., n or p channel Field Effect Transistors (FETs)). In oneembodiment, to avoid this issue, two current conveyors optimized fordifferent reference voltages with a sensor electrode switched betweenthem may be used. The current conveyors accumulate charge on at leasttwo capacitors for measuring differential or quadrature capacitances(e.g., two or alternately three or four capacitors may be used). Thisallows for modulating the sensor electrodes near the voltage railswithout significantly changing voltages (and charging internalcapacitances) on internal nodes of a current conveyor more than isnecessary for sensing charge coupled from the sensor electrodes.

Example Processing System

FIG. 5 shows a block diagram of an example processing system 110A,according to an embodiment. Processing system 110A may be utilized withan input device (e.g., in place of processing system 110 as part ofinput device 100), according to various embodiments. Processing system110A may be implemented with one or more Application Specific IntegratedCircuits (ASICSs), one or more Integrated Circuits (ICs), one or morecontrollers, or some combination thereof. In one embodiment, processingsystem 110A is communicatively coupled with a plurality of sensorelectrodes that implement a sensing region 120 of an input device 100.In some embodiments, processing system 110A and the input device 100, ofwhich it is a part, may be disposed in or communicatively coupled withan electronic system 150, such as a display device, computer, or otherelectronic system. Reference will be made to sensor electrode pattern200 of FIG. 2A and to one or more of FIGS. 6A, 6B, 6C and 6D indescribing example operations of processing system 100A.

In one embodiment, processing system 110A includes, among othercomponents: sensor module 510, and determination module 520. Processingsystem 110A and/or components thereof may be coupled with sensorelectrodes of a pattern of sensor electrodes, such as sensor electrodepattern 200 or 210, among others. For example, sensor module 510 iscoupled with one or more sensor electrodes (Y, X) of a sensor electrodepattern (e.g., sensor electrode pattern 200) of input device 100.

Sensor module 510 includes sensing circuitry that is coupled to sensorelectrodes of a sensor electrode pattern, such as via routing. Sensorcircuitry of sensor module 510 may include logic and, in manyembodiments, the sensor circuitry includes one or more amplifiers andassociated circuitry used for transmitting and receiving signals. Suchan amplifier may be interchangeably referred to as an “amplifier,” a“front-end amplifier,” a “receiver,” an “integrating amplifier,” a“differential amplifier,” “transimpedance amplifier”, or the like, andoperates, in some embodiments, to receive a resulting signal (e.g., theresulting signal may be a current signal) at an input and provide aproportional charge which may be output as an integrated voltage. In oneor more embodiments, the sensor module 510 maintains a low impedanceinput when measuring input current or charge. In some embodiments,sensor module 510 may also operate the same or a different amplifier todrive (or modulate) a transmitter signal onto a sensor electrode. Theresulting signal is from one or more sensor electrodes of a sensorelectrode pattern, such as sensor electrode pattern, and includeseffects that result from a transmitter signal that has been driven ontothe sensor electrode or onto another sensor electrode of the sensorelectrode pattern or effects corresponding to an input object proximatethe sensor electrode pattern to which sensor module 510 is coupled. Insome embodiments, a single amplifier may be coupled with and used toreceive a resulting signal exclusively from a single sensor electrode.In such embodiments, there would be at least one amplifier for eachsensor electrode in a sensor electrode pattern from which a signal isreceived. For example, in some embodiments, a first amplifier may becoupled with a first sensor electrode while a second amplifier iscoupled with a second sensor electrode, etc., for the number of sensorelectrodes from which signals are received by sensor module 510. Inother embodiments, multiple resulting signals from different sensorelectrodes may be summed by sensor module 510. For example, sensorelectrodes may be coupled to different ones of multiple currentconveyors whose output may summed into a single amplifier. In yet otherembodiments, multiple sensor electrodes may be coupled to a commonamplifier through a multiplexer. The multiplexer may select one sensorelectrode at a time or multiple sensor electrodes at a time. Furthermorea multiplexer may allow for sensor electrodes to be connected todifferent receivers or with different polarities or phases to the samereceiver.

Sensor module 510 operates to interact with the sensor electrodes of asensor electrode pattern, such as sensor electrode pattern 200, that areutilized to generate a sensing region. This includes operating one ormore sensor electrodes Y to be silent (e.g., not modulated relative toother sensor electrodes), to be driven with a transmitter signal, to beused for transcapacitive sensing (intra-set or set-to-set), and/or to beused for absolute capacitive sensing. This also includes operating oneor more sensor electrodes X to be silent, to be driven with atransmitter signal, to be used for transcapacitive sensing (intra-set orset-to-set), and/or to be used for absolute capacitive sensing.

During transcapacitive sensing, sensor module 510 operates to drive atransmitter signals on one or more sensor electrodes of a set of sensorelectrodes (e.g., one or more of sensor electrodes Y and/or one or moreof sensor electrodes X). A transmitter signal may be a square wave,trapezoidal wave, sine wave, or some other modulated signal. In a giventime interval, sensor module 510 may drive or not drive a transmittersignal (waveform) on one or more of the plurality of sensor electrodesof the sensor electrodes to which it is coupled. Sensor module 510 mayalso be utilized to couple one or more of the non-driven sensorelectrodes to high impedance, ground, or a constant voltage potential,or a modulated voltage when not driving a transmitter signal on suchsensor electrodes. In some embodiments, when performing transcapacitivesensing, sensor module 510 drives two or more transmitter electrodes ofa sensor electrode pattern at one time. When driving two or more sensorelectrodes of a sensor electrode pattern at once, the transmittersignals may be coded according to a coding scheme. The coded transmittersignals may include a varying phase, frequency and/or amplitude.

In various embodiments, the coding scheme may be at least substantiallyorthogonal. Further, the code(s) used may be altered, such as bylengthening or shortening a code to avoid or resist interference. Insome embodiments, sensor module 510 is configured to drive multiplesensor electrodes transmitter signals, where each of the multiple sensorelectrodes are each driven with a different transmitter signal and wherethe transmitter signals are each coded according to a coding scheme. Insuch embodiments, the sensor electrodes may be simultaneously driven.Sensor module 510 also operates to receive resulting signals, via asecond plurality of sensor electrodes during transcapacitive sensing.During transcapacitive sensing, received resulting signals correspond toand include effects corresponding to the transmitter signal(s)transmitted via sensor electrodes that are driven with transmittersignals. These transmitted transmitter signals may be altered or changedin the resulting signal at the receiver due to presence of an inputobject, stray capacitance, noise, interference, and/or circuitimperfections among other factors, and thus may differ slightly orgreatly from their transmitted versions.

In absolute capacitive sensing, sensor module 510 both drives a sensorelectrode relative to system ground or an input object and uses thatdriven sensor electrode to receive a resulting signal that results fromat least the signal driven on to the sensor electrode. In this manner,during absolute capacitive sensing, sensor module 510 operates to drivea signal on to and receive a signal from one or more of sensorelectrodes Y or X. During absolute capacitive sensing, the driven signalmay be referred to as an absolute capacitive sensing signal, transmittersignal, or modulated signal, and it is driven through a routing tracethat provides a communicative coupling between processing system 110Aand the sensor electrode(s) with which absolute capacitive sensing isbeing conducted. It should be appreciated that the transmitter signaldriven onto a particular sensor electrode for transcapacitive sensingand the transmitter signal driven on to that same particular electrodefor absolute capacitive sensing may be similar or identical.

In combined capacitive sensing, sensor module 510 may operate to drive amodulated transmitter signal on one sensor electrode of a sensorelectrode pattern while receiving resulting signals (which includeeffects that result from the transmitter signal) on at least one and upto all other sensor electrodes of the sensor electrode pattern, andwhile simultaneously also using the modulated transmitter signal tocharge and then receive resulting signals from the driven sensorelectrode for measuring absolute capacitance with that sensor electrode.That is, sensor module 510 may operate to both drive and receive signalsin a manner that facilitates simultaneous absolute capacitive sensingand transcapacitive sensing. It should be appreciated that, whenperforming combined capacitive sensing, sensor module 510 may drivetransmitter signals on more than one sensor electrode eitherconcurrently or at different times. Further, processing system 110A maybe configured to receive resulting signals corresponding to an absolutecapacitive coupling on more than one sensor electrode eitherconcurrently or at different times. As described earlier, thetransmitter signal may be substantially orthogonal, such that they areorthogonal in time, code, frequency, etc.

Determination module 520 may be implemented as hardware (e.g., hardwarelogic and/or other circuitry) and/or as a combination of hardware andinstructions stored in a non-transitory manner in a computer readablestorage medium.

In embodiments where transcapacitive sensing is performed, determinationmodule 520 operates to compute/determine a measurement of a change in atranscapacitive capacitive coupling between a first and second sensorelectrode during transcapacitive sensing. Determination module 520 thenuses such measurements to determine the positional information includingthe position of an input object (if any) with respect to sensing region.With reference to FIG. 2A, by way of example, the positional informationcan be determined from a capacitive image formed of capacitivecouplings/pixels like 290, a capacitive profile (transcapacitive orabsolute capacitive) formed from capacitive couplings/pixels like 295,297, and/or 299, or some combination thereof. With reference to FIG. 2B,the position information can be determined from a capacitive image orprofile formed of capacitive couplings/pixels like 280, 281, 282, 283,and/or 284, or some combination thereof. In some embodiments, multiplecapacitive images/profiles may be combined, correlated, and/or comparedto determine position information. The capacitive image(s)/profile(s)is/are determined by determination module 520 based upon resultingsignals acquired by sensor module 510. It is appreciated that, whenapplicable, determination module 520 operates to decode and reassemblecoded resulting signals to construct capacitive image(s)/profiles(s)from one or more transcapacitive scan of a plurality of sensorelectrodes.

In embodiments where absolute capacitive sensing is performed withsensor electrodes Y and/or X, determination module 520 also operates tocompute/determine a measurement of absolute capacitive coupling (alsoreferred to as background capacitance, C_(B)) to a sensor electrodewhich may be used to form a baseline. When an input object is within asensing region, this additionally includes a measuring of absolutecapacitance between the driven sensor electrode(s) and the input objectwhich may change the total absolute capacitance relative to thebaseline. With respect to the techniques described herein, determinationmodule 520 operates to determine an absolute capacitance of the sensorelectrode (e.g., sensor electrode X1) after an absolute capacitivesensing signal has been driven on the sensor electrode. Determinationmodule 520 operates to construct capacitive profiles from a plurality ofabsolute capacitance measurements on an axis. For example, in anembodiment where absolute capacitances are measured on individual sensorelectrodes X of sensor electrode pattern, determination module 520determines and constructs a first capacitive profile from these absolutecapacitive measurements. Similarly, in an embodiment where absolutecapacitances are measured on individual sensor electrodes Y of sensorelectrode pattern, determination module 520 determines and constructs asecond capacitive profile from these absolute capacitive measurements.In various embodiments, peaks in the measured response or significantchanges in curvature of the measurements relative to a baseline may beused to identify the location of input objects.

In embodiments where combined capacitive sensing is performed with asensor electrode pattern and produces resulting signals associated withboth absolute capacitive measurements and transcapacitive measurements,determination module 520 operates to determine capacitive images,transcapacitive profiles, and/or absolute capacitive profiles from thereceived resulting signals and can also combine, correlate, and/orcompare images, profiles, and/or individual capacitances determined fromresulting signals in order to determine position information of anyinput objects in a sensing region of the sensor electrode pattern. Insome embodiments, determination module 520 combines, correlates, and/orcompares these various measurements, profiles, and images, to determinepositional information with respect to an input object and/or todetermine instances when low ground mass effect (C_(XF) or C_(YF) issubstantially equal to C_(FG)) may make it seem as if an input object ispresent (e.g., in a capacitive image) but is not (because it does notalso exist a profile). Alternately, in various embodiments, where anobject appears significant in an intra-axis transcapacitive profile, butdoes not appear in the absolute profile, then the object may also beignored and not reported or absorbed into an image baseline (e.g., itmay be a coin or water droplet).

In some embodiments, processing system 110A includes decision makinglogic which directs one or more portions of processing system 110A, suchas sensor module 510 and/or determination module 520, to operate in aselected one of a plurality of different operating modes based onvarious inputs.

Processing System Operation

Several examples will now be discussed to illustrate, in part, theoperations of processing system 110A. Reference will be made to sensorelectrode pattern 200 of FIG. 2A in the description of these examples.In these, examples and elsewhere herein, it should be appreciated thattwo sets of substantially orthogonal sensor electrodes (e.g., sensorelectrodes X and sensor electrodes Y of sensor electrode pattern 200)are often described. It should be appreciated that the substantiallyorthogonal sets of sensor electrodes may be disposed in entirelydifferent layers from one another in the sensor electrode pattern,partially in the same layer as one another in the sensor electrodepattern, or entirely in the same common layer as one another in thesensor electrode pattern (e.g., a single layer sensor electrodepattern). Further with reference to FIG. 2B, the sensor electrodes maybe disposed in a matrix (regular or irregular) pattern. In such anembodiment, the sensor electrodes may include a similar shape and/orsize. Further, the sensor electrode may cover substantially the entiresensing area (e.g., with very small non-overlapping gaps). Routingtraces coupled to the sensor electrodes may be disposed on a commonlayer to sensor electrodes or on a different layer. The sensorelectrodes or grid electrodes between the sensor electrodes maysubstantially shield the routing traces from the effect of user inputs.Further, the routing traces may be included of a common material to thesensor electrodes or a different material. Further still, while notillustrated, one or more grid electrodes may be disposed between thesensor electrodes.

Consider an example where sensor electrode X1 of sensor electrodepattern 200 is driven by sensor module 510 with a modulated transmittersignal. In such an embodiment, first resulting signals (used forabsolute capacitive measurement) may be received from sensor electrodeX1 while second, third, fourth, etc. resulting signals (includingeffects of the modulated transmitter signal and used for transcapacitivemeasurement) are simultaneously received from one or more other sensorelectrodes (e.g., X2, X3, X4, Y1, Y2, Y3, Y4, and Y5) of the sensorelectrode pattern 200. For example, resulting signals may be receivedsimultaneously on up to all of sensor electrodes X2, X3, X4, Y1, Y2, Y3,Y4, and Y5. In some embodiments, processing system 110A (e.g., sensormodule 510) may drive a guarding signal on a sensor electrode that is inproximity to the sensor electrode being driven with the transmittersignal; the guarding signal may be in-phase with the transmitter signal.For example, if a modulated transmitter signal is driven on sensorelectrode X1, a guarding signal may be driven on sensor electrode X2 atthe same or at different amplitude that the modulated transmittersignal. In such a case, resulting signals may not be received from thesensor electrode that is used for guarding. In one specific embodiment,the guarding signal is in phase with and includes the same amplitude asthe transmitter signal. Further, in some embodiments, the sensorelectrode driven with the guard signal may be used to measure acapacitance to system ground.

Determination module 520 then determines a capacitive coupling (e.g., anabsolute capacitance) between an input object and the first sensorelectrode, e.g., X1, based on the first resulting signals and a changein capacitive coupling between the first and second sensor electrodesbased on the second resulting signals. In an embodiment where the secondsensor electrode is X2, a change in capacitive coupling between sensorelectrode X1 and sensor electrode X2 is determined; if the second sensorelectrode is Y5 the change in capacitive coupling between sensorelectrode X1 and sensor electrode Y5 is determined.

In some embodiments, sensor module 510 drives a modulated signal on onesensor electrode of a sensor electrode pattern and concurrently drives asecond modulated transmitter signal on a second sensor electrode of thesensor electrode pattern. In one such embodiment, the second modulatedsignal may have a phase opposite that of the modulated signal. Forexample, in one embodiment, when sensor module 510 drives a modulatedtransmitter signal on sensor electrode X1 of sensor electrode pattern200, sensor module 510 also drives a second transmitter signal (e.g.,having opposite phase of the transmitter signal) onto sensor electrodeY5. When sensor module 510 receives resulting signals from sensorelectrodes other than those being driven (e.g., sensor electrodes X2,X3, X4, Y2, Y3, Y4, and Y5) the resulting signals include effects fromboth the modulated transmitter signal and the second modulatedtransmitter signal. Alternatively, sensor electrodes X₁ and Y₁ may bedriven with signals being based on different codes or frequencies. Invarious embodiments, while sensor electrode Y₅ is modulated relative tosystem ground the one or more other sensor electrodes may not bemodulated relative to system ground. In such embodiments, sensorelectrode Y₅ may be configured to receive a resulting signal that may beused to determine a measure of the change in absolute capacitance ofsensor electrode Y₅ and changes in transcapacitances between sensorelectrode Y₅ and other sensor electrodes. By also driving sensorelectrode X₁ with a transmitter signal having an opposite phase, thechange in transcapacitance between Y₅ and X₁ may be larger than thechange between Y₅ and other sensor electrodes. In some embodiments, thischange may be almost twice as large.

In some embodiments, when a “one hot” technique is employed, after amodulated signal is driven on a first electrode sensor module 510 drivesa second modulated signal on a second and different sensor electrode.For example, if the modulated signal was driven on sensor electrode X1of sensor electrode pattern 200, first resulting signals could bereceived from sensor electrode X1, while second resulting signals arereceived from sensor electrode X2 and third resulting signals arereceived from sensor electrode Y5. At a time after the first modulatedsignal has been driven (e.g., not concurrent with) a second modulatedsignal is driven. The second modulated signal is not driven on sensorelectrode X1, but instead on another of the sensor electrodes (e.g., X2,X3, X4, Y1, Y2, Y3, Y4, or Y5). Resulting signals, used for absolutecapacitive sensing can then be received on the driven sensor electrodewhile simultaneously receiving resulting signals (including effects ofthe second modulated signals and used for transcapacitive sensing) fromany one or more of the non-driven sensor electrodes. For example, thesecond modulated signal can be driven on sensor electrode X2 and fourthresulting signals for absolute capacitive sensing can be received fromsensor electrode X2 while simultaneously receiving fifth and sixthresulting signals for transcapacitive sensing from sensor electrodes X1and Y5. Alternatively, in another example, the second modulated signalcan be driven on sensor electrode Y5 and fourth resulting signals forabsolute capacitive sensing can be received from sensor electrode Y5while simultaneously receiving fifth and sixth resulting signals fortranscapacitive sensing from sensor electrodes X1 and X2. Then, based atleast on the first, second, third, fourth, fifth and sixth resultingsignals, determination module 520 determines a first set-to-setcapacitive image along a first axis (e.g., an axis associated with the Xsensor electrodes), a second set-to-set capacitive image along a secondaxis (e.g., an axis associated with the Y sensor electrodes), anabsolute capacitive profile along the first axis, an absolute capacitiveprofile along the second axis, a transcapacitive profile along the firstaxis (e.g., an intra-set transcapacitive profile of the X electrodes),and a transcapacitive profile along the second axis (e.g., an intra-settranscapacitive profile of the Y electrodes).

Referring now to FIGS. 6A, 6B, 6C, and 6D, it should be appreciated thatFIGS. 6A, 6B, 6C, and 6D only illustrate sensor electrodes of sensorelectrode pattern 200 and eliminate depiction of insulating layers,substrates, routing traces, and the like to more clearly depictcapacitances measured in various embodiments. Additionally, in FIGS.6A-6D, for convenience of labeling capacitances, input object 140 isalso represented by a legend of F1 for “Finger 1.” It should beappreciated that the description and techniques presented with respectto FIGS. 6A-6D may similarly be applied to the sensor electrode pattern210 of FIG. 2B.

FIG. 6A shows an exploded front side elevation 610 of the example sensorelectrode pattern 200 of FIG. 2A with labeled capacitances, according toan embodiment. In FIG. 6A, in one embodiment, sensor module 510 drivesonly sensor electrode X1 with a modulated transmitter signal. This is anexample of the “one hot” technique that has been previously mentioned.Sensor module 510 receives resulting signals from sensor electrodes X1,X2, X3, X4, and Y5 which respectively allow determination module 520 todetermine capacitances C_(X1_ABS) (a combination of C_(X1F1) andC_(FG)), C_(X1X2), C_(X1X3), C_(X1X4) and C_(X1Y5). This allows thesensor module to determine the measurements substantially independently.Further, C_(X1F1) may be relatively stationary during measurements.C_(X1F1) allows for the coupling C_(X1) to ground of finger freespace tobe determined. Further, while not illustrated, a capacitance couplingexists between sensor electrode X1 and system ground (electrode G inFIG. 3A) and possibly other electrodes not shown, and depending on theirrelative voltage modulation (e.g. grounded or transmitting an oppositepolarity but not guarding X1), they may be included in a measurement ofcharge through X1 and affect measurement of C_(X1_ABS).

FIG. 6B shows an exploded left side elevation 620 of the example sensorelectrode pattern 200 of FIG. 2A with labeled capacitances, according toan embodiment. FIG. 6B continues the example illustrated in FIG. 6A andshows that when sensor electrode X1 is driven with a modulatedtransmitter signal sensor module 510 also receives resulting signalsfrom sensor electrodes Y1, Y2, Y3, and Y4, which respectively allowdetermination module 520 to determine capacitances C_(X1Y1), C_(X1Y2),C_(X1Y3), and C_(X1Y4). Following this one hot technique, other Xelectrodes can be driven in-turn, and resulting signals can be receivedin a similar fashion.

FIG. 6C shows an exploded front side elevation 630 of the example sensorelectrode pattern 200 of FIG. 2A with labeled capacitances, according toan embodiment. In FIG. 6C, in one embodiment, sensor module 510 drivesonly sensor electrode Y5 with a modulated transmitter signal. This is anexample of the “one hot” technique that has been previously mentioned.Sensor module 510 receives resulting signals from sensor electrodes X1,X2, X3, X4, and Y5 which respectively allow determination module 520 todetermine capacitances C_(Y5X1), C_(Y5X2), C_(Y5X3), C_(Y5X4) andC_(Y5_ABS) (a combination of C_(Y5F1) and C_(FG)).

FIG. 6D shows an exploded left side elevation 640 of the example sensorelectrode pattern 200 of FIG. 2A with labeled capacitances, according toan embodiment. FIG. 6D continues the example illustrated in FIG. 6C andshows that when sensor electrode Y5 is driven with a modulatedtransmitter signal sensor module 510 also receives resulting signalsfrom sensor electrodes Y1, Y2, Y3, and Y4, which respectively allowdetermination module 520 to determine capacitances C_(Y5Y1), C_(Y5Y2),C_(Y5Y3), and C_(Y5Y4). Following this one hot technique, other Yelectrodes can be driven in-turn, and resulting signals can be receivedin a similar fashion.

Example Methods of Operation

FIGS. 7A, 7B, 7C, 7D, 7E, 7F, and 7G illustrate a flow diagram ofvarious embodiments of a method of capacitive sensing. Steps ofembodiments of this method will be described with reference to elementsand/or components of one or more of FIGS. 1, 2A, 2B, 3A, 3B, 4, 5, 6A,6B, 6C, and 6D. It is appreciated that in some embodiments, the stepsmay be performed in a different order than described, that some of thedescribed steps may not be performed, and/or that one or more additionalsteps to those described may be performed. Likewise, it is appreciatedthat some steps are carried out by components of processing system ofFIG. 5, such as processing system 100A and/or stored instructionsimplemented by a processing system such as processing system 100A.

With reference to FIG. 7A, at step 701, in one embodiment, a modulatedsignal is driven onto a first sensor electrode of a sensor electrodepattern. With respect to the sensor electrode pattern, this can includedriving a modulated transmitter signal onto any one of the sensorelectrodes X or the sensor electrodes Y. For purposes of example, in oneembodiment, this includes processing system 110A (e.g., sensor module510 of FIG. 5) driving a modulated transmitter signal onto sensorelectrode X1 of the sensor electrode pattern.

With continued reference to FIG. 7A, at step 702, in one embodiment,first resulting signals are received from the first sensor electrode.Following the example started in step 701, if sensor electrode X1 is thefirst sensor electrode, then resulting signals are received from sensorelectrode X1 by processing system 110A (e.g., by sensor module 510 ofFIG. 5). The resulting signals may be used to determine a first chargemeasurement, Qx_(1F1) (or more generally the series capacitance throughC_(X1ABS)).

With continued reference to FIG. 7A, at step 703, in one embodiment,second resulting signals are received from a second sensor electrode ofthe sensor electrode pattern. The second resulting signals includeeffects corresponding to the modulated signal; and the first resultingsignals and the second resulting signals are simultaneously received.The second resulting signals may be used to determine a second chargemeasurement, Q_(X1X2). Following the example of 701 and 702, in anembodiment where sensor electrode X1 is driven with a modulatedtransmitter signal, second resulting signals can be received byprocessing system 110A (e.g., by sensor module 510 of FIG. 5) from anyof the remaining driven sensor electrodes of the sensor electrodepattern. For example, in one embodiment, processing system 110A (e.g.,sensor module 510 of FIG. 5) receives second resulting signals fromsensor electrode X2. In another embodiment, for example, processingsystem 110A (e.g., sensor module 510 of FIG. 5) receives the secondresulting signals from sensor electrode Y5. The second resulting signalsmay be used to determine a third charge measurement, Q_(X1Y5)

With continued reference to FIG. 7A, at step 704, in one embodiment, acapacitive coupling is determined between an input object and the firstsensor electrode based on the first resulting signals and change incapacitive coupling between the first and second sensor electrodes basedon the second resulting signals. With reference to the example describedin step 703, processing system 110A (e.g., determination module 520 ofFIG. 5) makes the determination of capacitive coupling in the mannerpreviously described herein. For example, this can include utilizing,combining, correlating, and/or comparing one or more absolute capacitiveprofiles, one or more transcapacitive profiles, and one or morecapacitive images which are determined from the resulting signals. Forexample, capacitance C_(X1F1) may be determined based on Qx_(1F1) and afirst delta voltage and a capacitance C_(X1X2) may be determined basedon Q_(X1X2) and a second delta voltage. The first delta voltage may bedefined as a first voltage and system ground and the second deltavoltage may be defined as the first voltage and a second voltage, wherethe second voltage may be ground.

With reference to FIG. 7B, as illustrated in step 705, in someembodiments, the method as described in steps 701-704 further includedriving a guarding signal is on a third sensor electrode of the sensorelectrode pattern. The third sensor electrode is proximate the firstsensor electrode and the guarding signal is in-phase with the modulatedsignal. In one embodiment, following the example discussed in step 701where a modulated transmitter signal is driven on sensor electrode X1, aguard signal is driven by processing system 110A (e.g., sensor module510 of FIG. 5) on sensor electrode X2. Sensor electrode X2 is proximateand immediately adjacent (no sensor electrodes between the two) tosensor electrode X1. Additionally, sensor electrodes X1 and X2 are inthe set of sensor electrodes X that are oriented along a common axiswith one another. In one embodiment, the guarding signal is the samemodulated transmitter signal that is driven on sensor electrode X1. Theguarding signal may be of lesser amplitude (i.e. underguarding), thesame amplitude, or greater amplitude (i.e. overguarding) than themodulated transmitter signal driven on sensor electrode X1. In anotherexample, if the modulated transmitter signal were being driven on sensorelectrode Y3, a guarding signal could be driven on one or more of sensorelectrodes Y2 and Y4.

With reference to FIG. 7C, as illustrated in step 706, in someembodiments, the method as described in steps 701-704 further includesdriving a second modulated signal on the second sensor electrode,wherein the second modulated signal has a phase opposite that of themodulated signal, and wherein the modulated signal and the secondmodulated signal are driven concurrently. In one embodiment, thisincludes driving the second modulated signal on a sensor electrode thatis oriented along a different axis that the axis of orientation of thefirst sensor electrode. With reference to the example of steps 701-704where the first sensor electrode is sensor electrode X1, a secondmodulated transmitter signal that is 180 degrees out of phase (butotherwise the same) can be driven on sensor electrode Y5 (or any othersensor electrode Y). The phase difference means that the signal to noiseratio is increased (e.g., one sensor electrode is being driven with ahigh signal while the other is being driven with a low signal, and thereis a difference in potential between the two that increases SNR). Insuch an embodiment, the previously discussed receipt of second resultingsignals from the second sensor electrode of the sensor electrodepattern, now includes: receiving the second resulting signals from thesecond sensor electrode of the sensor electrode pattern (e.g., by sensormodule 510), where the second resulting signals include effectscorresponding to the modulated signal driven on the first sensorelectrode and the second modulated signal driven on the second sensorelectrode.

With reference to FIG. 7D, as illustrated in step 707, in someembodiments, the method as described in steps 701-704 further includesdriving a second modulated signal onto the second sensor electrode ofthe sensor electrode pattern, where the modulated signal and the secondmodulated signal are driven during explicitly different time periods.For example, during the first time period the modulated signal may bedriven on sensor electrode X1 as described in steps 701-704; and duringa second, different time period that does not overlap with the firsttime period, the modulated signal is driven by processing system 110Aonto the second sensor electrode (e.g., onto sensor electrode X2 orsensor electrode Y5 in the previous example). In other embodiments, twoor more modulated signals based on distant (and possible substantiallyorthogonal) codes can be driven onto different corresponding sensorelectrodes. In such embodiments, each electrode may be decodedseparately.

In various embodiments, a first coding scheme may be used for absolutesensing a second and different coding scheme may be used fortranscapacitive sensing. For example, Hadadmard codes may be used forabsolute sensing while codes based on Linear Shift Registers may be usedfor transcapacitive sensing. Another method of simultaneously measuringindependent capacitive couplings is to use substantially orthogonalfrequencies such that an electrode (e.g., Y5) may be substantiallyguarding at one frequency (e.g. for a first absolute capacitivemeasurement by another electrode such as X1), while substantiallystationary at another (e.g. for a second transcapacitive measurement byanother electrode such as Y4), and even substantially opposite phase ata third frequency (e.g., for a third transcapacitive measurement byanother electrode such as X2). Yet another method is to make independentcapacitive measurements at different phases (e.g., 90 degrees fororthogonal sine and cosine modulations) such that measurements ofabsolute and transcapacitance can be made simultaneously.

With continued reference to FIG. 7D, at step 708, the method asdescribed in steps 701-704 and 707 further includes, receiving thirdresulting signals from the second sensor electrode. The third resultingsignals are received from the second sensor electrode after being drivenwith the second modulated signal. Following the ongoing example, in anembodiment where sensor electrode X2 is the second sensor electrode,sensor module 510 receives the third resulting signals from it; and inan embodiment where sensor electrode Y5 is the second sensor electrode,sensor module 510 receives the second resulting signals from it.

With continued reference to FIG. 7D, at step 709, the method asdescribed in steps 701-704, 707, and 708 further includes, receivingfourth resulting signals from the first sensor electrode. The fourthresulting signals include effects corresponding to the second modulatedsignal, and the third resulting signals and the fourth resulting signalsare simultaneously received. Following the ongoing example from steps701-704, the fourth resulting signals are received by sensor module 510of FIG. 5 from sensor electrode X1.

With continued reference to FIG. 7D, at step 710, the method asdescribed in steps 701-704, 707, 708, and 709 further includes,determining a change in capacitive coupling between an input object andthe second sensor electrode based on the third resulting signals andchange in capacitive coupling between the first and second sensorelectrodes based on the fourth resulting signals. In one embodiment,processing system 110A (e.g., determination module 520 of FIG. 5) makesthe determination of capacitive coupling in the manner previouslydescribed herein. For example, this can include utilizing combining,correlating, and/or comparing more than one type of combinedmeasurements of one or more absolute capacitive profiles, one or moretranscapacitive profiles, and one or more capacitive images which aredetermined from the resulting signals. In embodiments where more thantwo voltages are modulated, charges are accumulated on the receiverswhich are a combination of polarized charge on modulated capacitors.However, by balancing multiple measurements, independent capacitiveestimates may be made from a single combination signal.

With reference to FIG. 7E, as illustrated in step 711, in someembodiments, the method as described in steps 701-704 further includedriving a second modulated signal on a third sensor electrode of thesensor electrode pattern. The modulated signal and the second modulatedsignal are simultaneously driven, and the modulated signal and thesecond modulated signal are discrete signals based on different ones ofa plurality of codes. As with the first modulated signal, the secondmodulated signal is driven by processing system 110A (e.g., by sensormodule 510 of FIG. 5). Consider example described in steps 701-704,where sensor electrode X1 is the first sensor electrode. In oneembodiment while the modulated signal is being driving on sensorelectrode X1, a second modulated signal is driven on a different sensorelectrode, such as sensor electrode X3 or sensor electrode Y2. A varietyof coding schemes for simultaneously driving sensor electrodes are wellknown to those skilled in the arts of transcapacitive sensing, and manysuch coding schemes may be similarly applied to drive the modulatedsignal and the second modulated signal as signals coded differently fromone another.

With continued reference to FIG. 7E, at step 712, the method asdescribed in steps 701-704 and 711 further includes, receiving thirdresulting signals from the third sensor electrode that has been drivenwith the second modulated signal. Processing system 110A (e.g., sensormodule 510 of FIG. 5) can receive the third resulting signals. Due totwo differently coded modulated signals being driven simultaneously, thepreviously described second resulting signals will further includeeffects corresponding to the second modulated signal as well as effectscorresponding to the modulated signal.

With reference to FIG. 7F, as illustrated in step 713, in someembodiments, the method as described in steps 701-704 further includesreceiving third resulting signals with a third sensor electrode of thesensor electrode pattern, where the third resulting signals are receivedsimultaneously with the first and second resulting signals. Consider theexample described in steps 701 and 704, in one embodiment, thirdresulting signals are received from sensor electrode X3, fourthresulting signals from sensor electrode X4, fifth resulting signals fromsensor electrode Y4, sixth resulting signals from sensor electrode Y3,seventh resulting signals from sensor electrode Y2, and eighth resultingsignals from sensor electrode Y1. Each of the third through eighthresulting signals includes effects from the modulated signal driven onsensor electrode X1. All of these resulting signals can be utilized byprocessing system 110A (e.g., by determination module 520 of FIG. 5) todetermine the position of an input object with respect to the sensorelectrode pattern.

With reference to FIG. 7G, as illustrated in step 714, in someembodiments, the method as described in steps 701-704 utilized a sensorelectrode pattern that includes a first plurality of sensor electrodesdisposed along a first axis (e.g., the axis of the long edge of eachsensor electrodes X) and a second plurality of sensor electrode disposedalong a second axis (e.g., the axis of the long edge of each of thesensor electrodes Y), where the first axis is substantially orthogonalto the second axis and where the first plurality of sensor electrodesincludes the first and second sensor electrodes. In one such embodiment,the method as described in steps 701-704 further includes receivingthird resulting signals with a third sensor electrode of the secondplurality of sensor electrodes, the third resulting signals includeseffects corresponding to the modulated signal and wherein the thirdresulting signals include effects corresponding to the modulated signaldriven onto the first sensor electrode. Consider an embodiment where thefirst sensor electrode is sensor electrode X1 and the second sensorelectrode is X2, then in step 714, processing system 110A (e.g., sensormodule 510) receives third resulting signals from a sensor electrode ofthe Y sensor electrodes, such as sensor electrode Y5.

With continued reference to FIG. 7G, at step 715, the method asdescribed in steps 701-704 and 714 further includes, driving a secondmodulated signal onto the third sensor electrode. Following the aboveexample, where sensor electrode Y5 is the third sensor electrode, in oneembodiment, processing system 110A (e.g., sensor module 510 of FIG. 5)drives a second modulated transmitter signal on sensor electrode Y5. Inone embodiment, this second transmitter signal may be modulated in thesame or similar manner as the transmitter signal. In one embodiment, thesecond modulated transmitter signal driven at a different time that doesnot overlap with the driving of the transmitter signal.

With continued reference to FIG. 7G, at step 716, the method asdescribed in steps 701-704, 714, and 715 further includes, receivingfourth resulting signals with the third sensor electrode. Following theexample where sensor electrode Y5 is the third sensor electrode, in oneembodiment, processing system 110A (e.g., sensor module 510 of FIG. 5)receives fourth resulting signals from sensor electrode Y5.

With continued reference to FIG. 7G, at step 717, the method asdescribed in steps 701-704, 714, 715, and 716 further includes,receiving fifth resulting signals with the first sensor electrode, thefifth resulting signals including effects corresponding to the secondmodulated signal. Following the example where sensor electrode Y5 is thethird sensor electrode and sensor electrode X1 is the first sensorelectrode, in one embodiment, processing system 110A (e.g., sensormodule 510 of FIG. 5) receives the fifth resulting signals from sensorelectrode X1.

With continued reference to FIG. 7G, at step 718, the method asdescribed in steps 701-704, 714, 715, 716, and 717 further includes,receiving sixth resulting signals with the second sensor electrode, thesixth resulting signals including effects corresponding to the secondmodulated signal. Following the example where sensor electrode Y5 is thethird sensor electrode, sensor electrode X1 is the first sensorelectrode, and sensor electrode X2 is the second sensor electrode, inone embodiment, processing system 110A (e.g., sensor module 510 of FIG.5) receives the sixth resulting signals from sensor electrode X2.

With continued reference to FIG. 7G, at step 719, the method asdescribed in steps 701-704, 714, 715, 716, 717, and 718 furtherincludes, determining a first capacitive image along the first axis, asecond capacitive image along the second axis, an absolute capacitiveprofile along the first axis, an absolute capacitive profile along thesecond axis, a transcapacitive profile along the first axis, and atranscapacitive profile along the second axis based on the first,second, third, fourth, fifth and sixth resulting signals. It isappreciated that many more modulated signals may be driven using the“one hot” technique (for example) described herein or using othertechniques. Other resulting signals may be received and included in thefirst and second capacitive images, the first and second transcapacitiveprofiles, and the first and second absolute capacitive profiles.

Combined Capacitive Sensing

In some embodiments, combined sensing is performed by driving a sensingsignal onto a sensor electrode for the purposes of measuring absolutecapacitance with that sensor electrode and, simultaneously with thedriving of that sensor electrode, other sensor electrodes that cross anddo not cross that sensor electrode may be used as receivers to obtaintranscapacitive measurements between themselves and the driven sensorelectrode.

In combined capacitive sensing, a sensor module may operate to drive amodulated transmitter signal on one sensor electrode of a sensorelectrode pattern while receiving resulting signals (which involveeffects that result from the transmitter signal) on at least one and upto all other sensor electrodes of the sensor electrode pattern, andwhile simultaneously also using the modulated transmitter signal tocharge and then receive resulting signals from the driven sensorelectrode for measuring absolute capacitance with that sensor electrode.That is, the sensor module may operate to both drive and receive signalsin a manner that facilitates simultaneous absolute capacitive sensingand transcapacitive sensing. It should be appreciated that, whenperforming combined capacitive sensing, the sensor module may drivetransmitter signals on more than one sensor electrode eitherconcurrently or at different times. Further, a processing system may beconfigured to receive resulting signals corresponding to an absolutecapacitive coupling on more than one sensor electrode eitherconcurrently or at different times. As described earlier, thetransmitter signal may be substantially orthogonal, such that they areorthogonal in time, code, frequency, etc.

Turning to FIG. 8, a capacitive sensing scheme in accordance with one ormore embodiments is illustrated. In particular, a sensing signal (805)(also called k_(TX)V_(DD)), or another sensing signal with a modulatedamplitude relative to a receiver electrode is driven along varioustransmitter electrodes (TX) (815), which produces various resultingsignals. Simultaneously, another sensing signal (810) (also called αVDD)is driven along various receiver electrodes (RX) (820). The compositeresulting signals are obtained by a receiver (not shown) to generate acombination signal. In particular, C_(T) (838) is a transcapacitivecoupling between the transmitter electrode (815) and the receiverelectrode (820), C_(H) (832) is the capacitance to earth ground of aninput object (860), e.g., a user's hand, C_(B,TX) (840) is the absolutecapacitance (capacitance to system ground) at the transmitter electrode(815), C_(B,RX) (842) is the absolute capacitance at the receiverelectrode (820), ΔC_(F,TX) (836) is the capacitance between thetransmitter electrode (815) and the input object (860), ΔC_(F,RX) (834)is the capacitance between the receiver electrode (820) and the inputobject (860), and C_(P) (844) is the reference capacitance to earthground in an input device (not shown) implementing the capacitivesensing scheme.

Continuing with FIG. 8, a measured capacitive profile signal of an inputdevice may increase when measuring both a transcapacitive signal and anabsolute capacitive signal. As such, a combination signal may be the sumof a transcapacitive signal and an absolute capacitive signal.Accordingly, the combination signal may provide a transcapacitive andabsolute capacitive profile for capacitive sensing.

Turning to FIG. 9, a flowchart in accordance with one or moreembodiments is shown. FIG. 9 describes a method for performingcapacitive sensing. More specifically, using the method of FIG. 9, anabsolute capacitance measurement is indirectly obtained byreconstruction from a combination of capacitive sensing measurements.

In a traditional absolute capacitance measurement, all electrodes may bedriven at the same voltage or potential. Accordingly, the charge that ismeasured may be defined asQ _(Tx) ^(ABS) =C _(FTx)(ϕ_(Tx)−ϕ_(F))+C _(BTx)(ϕ_(Tx)−ϕ_(B)),  (1)where Q_(Tx) ^(ABS) is the charge associated with the Tx electrode andresulting from an input object such as a finger being present near theTx electrode in an absolute capacitance sensing scheme. C_(FTx) is thecapacitance from the Tx electrode to the input object, C_(BTx) is thecapacitance from the Tx electrode to a background, Φ_(R) is the voltageor potential of the Tx electrode, Φ_(F) is the voltage or potential ofthe input object, and Φ_(B) is the voltage or potential of thebackground. The background capacitive coupling C_(BTx) may be relativelyhigh, in particular in comparison to the capacitive coupling to theinput object C_(FTx). The background capacitive coupling may beresulting from capacitive interactions of the electrode Tx withsurrounding components such as a housing, a screen, background plane,etc. The background capacitance may be particularly high when abackground plane or other components are particularly close to theelectrode Tx, which is not uncommon in highly integrated devices, suchas portable devices. In some scenarios, C_(FTx) is in the range of a fewpico-farads, whereas C_(BTx) may be 10 times greater, or more. Forexample, C_(BTx) may be more than 300 times greater than C_(FTx). Onemay assume that both the input object and the background are grounded.Accordingly, the parasitic background charge may be C_(BTx)Φ_(Tx). Thisparasitic background charge may be measured, e.g., when no input objectis present in the vicinity of the electrode Tx, to obtain a baselineterm which can be subtracted from an actual measurement to isolate theeffect associated with the presence of the input object. However, thenecessity of a high level of charge resulting from C_(BTx),nevertheless, requires an increased charge, while only a small portionof that charge would be attributed to C_(FTx). As a result, the signalto noise ratio of such a measurement may be poor, and the sensingcircuitry performing the measurement may even saturate.

In one or more embodiments, to reduce the high level of charge, acombination capacitance sensing measurement rather than an absolutecapacitance sensing measurement is performed. The charge that ismeasured may be defined asQ _(Tx) ^(TABS) =C _(FTx)(ϕ_(tx)−ϕ_(F))+C _(BTx)(ϕ_(Tx)−ϕ_(B))−Σ_(k=1)^(N) C _(tF) _(k) (ϕ_(Rx) _(k) −ϕ_(Tx)),  (2)where C_(Tx) ^(TABS) is the charge associated with the Tx electrode andresulting from an input object such as a finger being present near theTx electrode in a combined capacitance sensing scheme. C_(tF) _(k) isthe transcapacitance from the Tx electrode to the k-th of N Rxelectrodes with a potential or voltage ϕ_(Rx) _(k) . While in atraditional absolute capacitance sensing configuration, ϕ_(Rx) _(k)−ϕ_(Tx)=0 for all k, thus resulting in the configuration described byequation 1, in one or more embodiments, ϕ_(Rx) _(k) >ϕ_(Tx), therebyresulting in the combination capacitance sensing measurement of equation2 requiring a smaller charge than the absolute capacitance sensingmeasurement of equation 1.

The sensing configuration of equation 2 is illustrated in FIG. 12, inwhich a finger serves as an input object. For simplicity, only a singleRx electrode is shown, i.e., N=1.

While the combined capacitance sensing scheme, therefore, addresses theconcern of the potentially excessive charge requirement of thetraditional absolute capacitance sensing scheme, the resultingcapacitance values may deviate from those obtained using traditionalabsolute capacitance sensing schemes. An illustration of thesedeviations (1300) is provided in FIG. 13. An absolute capacitanceprofile, C_(FTx) ^(ABS), is shown (solid line). Further, a combinedcapacitance profile, C_(FTx) ^(TABS), is shown (dash-dotted line). It isapparent that the amplitude and shape of the combined capacitanceprofile significantly deviates from the absolute capacitance profile. Byinspection of equation 2, one may decide to reconstruct the absolutecapacitance from the obtained combined capacitance by simply adjustingthe obtained combined capacitance for the additional presence of thetranscapacitance. The result is shown in FIG. 13 (dotted line). Due tonoise, the obtained reconstruction poorly matches the absolutecapacitance profile.

In one or more embodiments, an accurate absolute capacitance profile isreconstructed, while providing the benefit of lower charges measurement.The subsequently described embodiments essentially perform a combinedcapacitance sensing with the characteristics of an absolute capacitancesensing scheme, resulting in the dashed line (C_(FRx) ^(TABS)+C_(FRx)^(PROJ)) in FIG. 13.

Continuing with the discussion of FIG. 9, in Step 900, a combinationsignal is obtained through measurement using sensor electrodes. Theobtained combination signal may be governed by equation 2, in a mannerreducing the necessary charge, e.g., by an appropriate selection ofϕ_(Rx) _(k) and ϕ_(Tx). A detailed description of Step 900 is providedin. FIG. 10, and an example of an obtained combination signal profile isshown in FIG. 13 (dash-dotted line C_(FRx) ^(TABS)).

In Step 902, a transcapacitance signal or multiple transcapacitancesignals is/are obtained through measurement using the sensor electrodes.The measurement of the transcapacitance signal(s) may be performedseparately from the measurement of the combination signal of Step 900,e.g., immediately before or after Step 900, such that during theexecution of both Steps 900 and 902, the input object is equallypresent. A detailed description of Step 902 is provided in FIG. 11, andis denoted by C_(FRx) ^(PROJ) in the example of FIG. 13.

In Step 904, a background capacitance is obtained. While Step 904 isshown in sequence with Steps 900, 902 and 906, those skilled in the artwill appreciate that Step 904 may be performed separately, e.g., when adevice calibration is performed. Specifically, the backgroundcapacitance may be determined in an absolute capacitance measurementconfiguration described by equation 1, in a scenario in which no inputobject is present. Further, it may be assumed that the backgroundpotential, Φ_(B), is ground, i.e., 0V. As a result, the backgroundcapacitance, C_(BTx), can be determined directly based on the drivingvoltage amplitude Φ_(Tx) of the Tx electrode and the measured chargeQ_(Tx) ^(ABS).

In Step 906, an absolute capacitance signal is computed by combining thetranscapacitance signal measurement of Step 902 with the combinationsignal measurement of Step 900 and with the background capacitance ofStep 904. The combination may be performed based on equation 2. Morespecifically, in equation 2, after the execution of Steps 900, 902 and904, the charge Q_(Tx) ^(TABS) is measured, the voltages or potentialsΦ_(Tx), and Φ_(R)A are known, and Φ_(F) and Φ_(B) may be assumed to betied to ground, thereby enabling reconstruction of the absolutecapacitance C_(FTx).

While FIG. 9 describes the use of a single Tx sensing electrode, in someembodiments a capacitive scan may be performed by at least one axis of agrid electrode array, in which multiple electrodes may operate as Txsensing electrodes while other electrodes may operate as Rx sensingelectrodes. Capacitance signal profiles may thus be obtained along axesof the grid electrode array. Such capacitance signal profiles (1300) areshown in FIG. 13.

In FIG. 13, the restored absolute capacitance signal profile (dashedline), obtained after completion of Step 904, closely matches theabsolute capacitance signal profile (solid line), in accordance with oneor more embodiments. A reliable absolute capacitance signal may thus beavailable, despite a reduction in the charge being used for themeasurement. As a result of the reduced charge, clipping issues may beavoided. This may facilitate measurement circuit design and may actuallybe a necessity for certain circuit designs, in particular in presence ofhigh background capacitances.

In one or more embodiments, the capacitive sensing according to themethod of FIG. 9 results in an increased signal-to-noise-ratio (SNR) incomparison to an absolute capacitance measurement. Moreover, an inputdevice operating according to the method of FIG. 9 may not requiresignificant baseline correction. Less baseline correction may benecessary in comparison to absolute capacitance measurements. Thus, thecircuit area in the processing system designated for charge subtractionmay be reduced.

The restored absolute capacitance signal may subsequently be used tocompute positional information of an input object, and/or to performother computations such as those required to execute a low ground mass(LGM) detection and/or correction algorithm.

Turning to FIG. 10, a method for obtaining a combination signal, inaccordance with one or more embodiments, is shown.

In Step 1000, ϕ_(Tx), the driving voltage amplitude of the Tx electrode,and ϕ_(Rx) _(k) , the driving voltage amplitude of the Rx electrode(s),are selected. In one or more embodiments, ϕ_(Rx) _(k) >ϕ_(Tx). Forexample, ϕ_(Rx) _(k) =6V and ϕ_(Tx)=1.5V.

In Step 1002, a modulated signal with the amplitude Φ_(R) is driven onthe sensor electrode Tx in accordance with one or more embodiments. Insome embodiments, the modulated signal may be similar to the modulatedsignals described in FIG. 5 and/or the sensing signal (805) describedabove in FIG. 8 and the accompanying description. Likewise, sensorelectrode Tx may be a sensor electrode similar to the transmitterelectrode (815) described in FIG. 8, the transmitter electrodes and/orreceiver electrodes described in FIG. 1, and the sensor electrodesdescribed in FIGS. 2A, 2B, 3A, 3B, 4, 5, 6A, 6B, 6C, and 6D and theaccompanying description. In some embodiments, Step 1002 is performedfor multiple sensor electrodes, Tx.

In Step 1004, a modulated signal with the amplitude ϕ_(Rx) _(k) isdriven on a sensor electrode Rx in accordance with one or moreembodiments. The modulated signals in Steps 1002 and 1004 may be drivenconcurrently during a combined capacitive scan of a sensing region. Themodulated signal on sensor electrode Rx may be in phase with themodulated signal on sensor electrode Tx. Further, the modulated signalson sensor electrodes Tx and Rx may have the same waveforms withamplitudes ϕ_(Tx) and ϕ_(Rx) _(k) , respectively. k Rx electrodes may bedriven simultaneously.

In Step 1006, resulting signals are received simultaneously from sensorelectrode Tx and sensor electrode(s) Rx in accordance with one or moreembodiments. The resulting signal obtained on sensor electrode Tx maycorrespond to an absolute capacitance between the sensor electrode andthe input object. Likewise, the resulting signal on sensor electrode Rxmay correspond to a transcapacitance between sensor electrode Tx andsensor electrode Rx in presence of the input object.

In Step 1008, a combination signal is generated based on resultingsignals from sensor electrode Tx and sensor electrode Rx in accordancewith one or more embodiments. Sensor circuitry may be coupled to sensorelectrode Tx and sensor electrode(s) Rx, and the sensor circuitry may beconfigured to combine the two or more resulting signals into a singlecombination signal. Likewise, a processing system may perform variousanalog signal conditioning on the combination signal, e.g., with respectto filtering, amplifying, and/or adjusting one or more amplitudes of thecombination signal.

Turning to FIG. 11, method for obtaining a transcapacitance signal, inaccordance with one or more embodiments, is shown.

In Step 1100, Φ_(Tx), the driving voltage amplitude of the Tx electrode,and ϕ_(Rx) _(k) , the driving voltage amplitude of the Rx electrode(s),are set. In one or more embodiments, ϕ_(Rx) _(k) is set to 0V or to aground potential such as Φ_(B). For example, ϕ_(Rx) _(k) =0V andϕ_(Tx)=6V.

In Step 1102, a modulated signal with the amplitude Φ_(R) is driven onthe sensor electrode Tx in accordance with one or more embodiments. Insome embodiments, the modulated signal may be similar to the modulatedsignals described in FIG. 5 and/or the sensing signal (805) describedabove in FIG. 8 and the accompanying description. In some embodiments,Step 1102 is performed for multiple sensor electrodes, Tx.

In Step 1104, the sensor electrode(s) Rx is/are set to the constantpotential ϕ_(Rx) _(k) while the electrode Tx is driven as described inStep 1102, in accordance with one or more embodiments.

In Step 1106, a resulting signal or signals is/are received from sensorelectrode(s) Rx in accordance with one or more embodiments. Theresulting signal on sensor electrode Rx may correspond to changes in atranscapacitance between sensor electrode Tx and sensor electrode Rx.

Turning to FIG. 12, a capacitive sensing scenario (1200) in accordancewith one or more embodiments is shown. The capacitive sensing scenario(1200) is comparable to the previously illustrated scenarios of FIGS.6A, 6B, 6C, and 6D. For simplicity, only a single Tx electrode, a singleRx electrode, a background and an input object with the associatedcapacities C_(FTx), C_(tF) and C_(BTx) are shown. FIG. 12 is used inconjunction with equation 2 to illustrate absolute capacitive sensing,transcapacitive sensing and combined capacitive sensing, depending onthe selection of the voltages of the electrodes Tx and Rx, as previouslydiscussed.

Turning to FIG. 13, exemplary sensing profiles (1300) are shown. FIG. 13shows a traditionally obtained reference absolute capacitance profileC_(FRx) ^(ABS) (solid line). FIG. 13 further shows a combinedcapacitance profile C_(FRx) ^(TABS) (dash-dotted line). In addition,FIG. 13 shows a reconstructed absolute capacitance profile (dottedline), obtained by adjusting the combined capacitance profile for theadditional presence of the transcapacitance. FIG. 13 further shows analternatively obtained absolute capacitance profile (dashed line),obtained by adjusting the combined capacitance profile using aseparately measured transcapacitance profile, in accordance with one ormore embodiments.

Embodiments may be implemented on a computing system. Any combination ofmobile, desktop, server, router, switch, embedded device, or other typesof hardware may be used. For example, as shown in FIG. 14, the computingsystem (1400) may include one or more computer processors (1402),non-persistent storage (1404) (e.g., volatile memory, such as randomaccess memory (RAM), cache memory), persistent storage (1406) (e.g., ahard disk, an optical drive such as a compact disk (CD) drive or digitalversatile disk (DVD) drive, a flash memory, etc.), a communicationinterface (1412) (e.g., Bluetooth interface, infrared interface, networkinterface, optical interface, etc.), and numerous other elements andfunctionalities.

The computer processor(s) (1402) may be an integrated circuit forprocessing instructions. For example, the computer processor(s) may beone or more cores or micro-cores of a processor. The computing system(1400) may also include one or more input devices (1410), such as atouchscreen, keyboard, mouse, microphone, touchpad, electronic pen, orany other type of input device.

The communication interface (1412) may include an integrated circuit forconnecting the computing system (1400) to a network (not shown) (e.g., alocal area network (LAN), a wide area network (WAN) such as theInternet, mobile network, or any other type of network) and/or toanother device, such as another computing device.

Further, the computing system (1400) may include one or more outputdevices (1408), such as a screen (e.g., a liquid crystal display (LCD),a plasma display, touchscreen, cathode ray tube (CRT) monitor,projector, or other display device), a printer, external storage, or anyother output device. One or more of the output devices may be the sameor different from the input device(s). The input and output device(s)may be locally or remotely connected to the computer processor(s)(1402), non-persistent storage (1404), and persistent storage (1406).Many different types of computing systems exist, and the aforementionedinput and output device(s) may take other forms.

Software instructions in the form of computer readable program code toperform embodiments of the disclosed technology may be stored, in wholeor in part, temporarily or permanently, on a non-transitory computerreadable medium such as a CD, DVD, storage device, a diskette, a tape,flash memory, physical memory, or any other computer readable storagemedium. Specifically, the software instructions may correspond tocomputer readable program code that, when executed by a processor(s), isconfigured to perform one or more embodiments of the disclosedtechnology.

Shared memory refers to the allocation of virtual memory space in orderto substantiate a mechanism for which data may be communicated and/oraccessed by multiple processes. In implementing shared memory, aninitializing process first creates a shareable segment in persistent ornon-persistent storage. Post creation, the initializing process thenmounts the shareable segment, subsequently mapping the shareable segmentinto the address space associated with the initializing process.Following the mounting, the initializing process proceeds to identifyand grant access permission to one or more authorized processes that mayalso write and read data to and from the shareable segment. Changes madeto the data in the shareable segment by one process may immediatelyaffect other processes, which are also linked to the shareable segment.Further, when one of the authorized processes accesses the shareablesegment, the shareable segment maps to the address space of thatauthorized process. Often, only one authorized process may mount theshareable segment, other than the initializing process, at any giventime.

Other techniques may be used to share data, such as the various datadescribed in the present application, between processes withoutdeparting from the scope of the disclosed technology. The processes maybe part of the same or different application and may execute on the sameor different computing system.

Rather than or in addition to sharing data between processes, thecomputing system performing one or more embodiments of the disclosedtechnology may include functionality to receive data from a user. Forexample, in one or more embodiments, a user may submit data via agraphical user interface (GUI) on the user device. Data may be submittedvia the graphical user interface by a user selecting one or moregraphical user interface widgets or inserting text and other data intographical user interface widgets using a touchpad, a keyboard, a mouse,or any other input device. In response to selecting a particular item,information regarding the particular item may be obtained frompersistent or non-persistent storage by the computer processor. Uponselection of the item by the user, the contents of the obtained dataregarding the particular item may be displayed on the user device inresponse to the user's selection.

By way of another example, a request to obtain data regarding theparticular item may be sent to a server operatively connected to theuser device through a network. For example, the user may select auniform resource locator (URL) link within a web client of the userdevice, thereby initiating a Hypertext Transfer Protocol (HTTP) or otherprotocol request being sent to the network host associated with the URL.In response to the request, the server may extract the data regardingthe particular selected item and send the data to the device thatinitiated the request. Once the user device has received the dataregarding the particular item, the contents of the received dataregarding the particular item may be displayed on the user device inresponse to the user's selection. Further to the above example, the datareceived from the server after selecting the URL link may provide a webpage in Hyper Text Markup Language (HTML) that may be rendered by theweb client and displayed on the user device.

Once data is obtained, such as by using techniques described above orfrom storage, the computing system, in performing one or moreembodiments of the disclosed technology, may extract one or more dataitems from the obtained data. For example, the extraction may beperformed as follows by the computing system (1400) in FIG. 14. First,the organizing pattern (e.g., grammar, schema, layout) of the data isdetermined, which may be based on one or more of the following: position(e.g., bit or column position, Nth token in a data stream, etc.),attribute (where the attribute is associated with one or more values),or a hierarchical/tree structure (consisting of layers of nodes atdifferent levels of detail—such as in nested packet headers or nesteddocument sections). Then, the raw, unprocessed stream of data symbols isparsed, in the context of the organizing pattern, into a stream (orlayered structure) of tokens (where each token may have an associatedtoken “type”).

Next, extraction criteria are used to extract one or more data itemsfrom the token stream or structure, where the extraction criteria areprocessed according to the organizing pattern to extract one or moretokens (or nodes from a layered structure). For position-based data, thetoken(s) at the position(s) identified by the extraction criteria areextracted. For attribute/value-based data, the token(s) and/or node(s)associated with the attribute(s) satisfying the extraction criteria areextracted. For hierarchical/layered data, the token(s) associated withthe node(s) matching the extraction criteria are extracted. Theextraction criteria may be as simple as an identifier string or may be aquery presented to a structured data repository (where the datarepository may be organized according to a database schema or dataformat, such as XML).

The extracted data may be used for further processing by the computingsystem. For example, the computing system of FIG. 14, while performingone or more embodiments of the disclosed technology, may perform datacomparison. Data comparison may be used to compare two or more datavalues (e.g., A, B). For example, one or more embodiments may determinewhether A>B, A=B, A !=B, A<B, etc. The comparison may be performed bysubmitting A, B, and an opcode specifying an operation related to thecomparison into an arithmetic logic unit (ALU) (i.e., circuitry thatperforms arithmetic and/or bitwise logical operations on the two datavalues). The ALU outputs the numerical result of the operation and/orone or more status flags related to the numerical result. For example,the status flags may indicate whether the numerical result is a positivenumber, a negative number, zero, etc. By selecting the proper opcode andthen reading the numerical results and/or status flags, the comparisonmay be executed. For example, in order to determine if A>B, B may besubtracted from A (i.e., A−B), and the status flags may be read todetermine if the result is positive (i.e., if A>B, then A−B>0). In oneor more embodiments, B may be considered a threshold, and A is deemed tosatisfy the threshold if A=B or if A>B, as determined using the ALU. Inone or more embodiments of the disclosed technology, A and B may bevectors, and comparing A with B requires comparing the first element ofvector A with the first element of vector B, the second element ofvector A with the second element of vector B, etc. In one or moreembodiments, if A and B are strings, the binary values of the stringsmay be compared.

The computing system in FIG. 14 may implement and/or be connected to adata repository. For example, one type of data repository is a database.A database is a collection of information configured for ease of dataretrieval, modification, re-organization, and deletion. DatabaseManagement System (DBMS) is a software application that provides aninterface for users to define, create, query, update, or administerdatabases.

The computing system of FIG. 14 may include functionality to present rawand/or processed data, such as results of comparisons and otherprocessing. For example, presenting data may be accomplished throughvarious presenting methods. Specifically, data may be presented througha user interface provided by a computing device. The user interface mayinclude a GUI that displays information on a display device, such as acomputer monitor or a touchscreen on a handheld computer device. The GUImay include various GUI widgets that organize what data is shown as wellas how data is presented to a user. Furthermore, the GUI may presentdata directly to the user, e.g., data presented as actual data valuesthrough text, or rendered by the computing device into a visualrepresentation of the data, such as through visualizing a data model.

For example, a GUI may first obtain a notification from a softwareapplication requesting that a particular data object be presented withinthe GUI. Next, the GUI may determine a data object type associated withthe particular data object, e.g., by obtaining data from a dataattribute within the data object that identifies the data object type.Then, the GUI may determine any rules designated for displaying thatdata object type, e.g., rules specified by a software framework for adata object class or according to any local parameters defined by theGUI for presenting that data object type. Finally, the GUI may obtaindata values from the particular data object and render a visualrepresentation of the data values within a display device according tothe designated rules for that data object type.

Data may also be presented through various audio methods. In particular,data may be rendered into an audio format and presented as sound throughone or more speakers operably connected to a computing device.

Data may also be presented to a user through haptic methods. Forexample, haptic methods may include vibrations or other physical signalsgenerated by the computing system. For example, data may be presented toa user using a vibration generated by a handheld computer device with apredefined duration and intensity of the vibration to communicate thedata.

The above description of functions present only a few examples offunctions performed by the computing system of FIG. 14. Other functionsmay be performed using one or more embodiments of the disclosedtechnology.

The examples set forth herein were presented in order to best explain,to describe particular applications, and to thereby enable those skilledin the art to make and use embodiments of the described examples.However, those skilled in the art will recognize that the foregoingdescription and examples have been presented for the purposes ofillustration and example only. The description as set forth is notintended to be exhaustive or to limit the embodiments to the preciseform disclosed.

What is claimed is:
 1. A processing system comprising: a sensor module,the sensor module configured to: perform a first measurement to obtain acombination signal using a first sensor electrode and a second sensorelectrode among a plurality of sensor electrodes by: selecting a firstdriving voltage amplitude for the first sensor electrode and a seconddriving voltage amplitude for the second sensor electrode, wherein thesecond driving voltage amplitude is greater than the first drivingvoltage amplitude; driving the first electrode using a first modulatedsignal with the first driving voltage amplitude and simultaneouslydriving the second electrode using a second modulated signal with thesecond driving voltage amplitude; and receiving, simultaneously with thedriving of the first and the second electrodes, a first resulting signalfrom the first electrode and a second resulting signal from the secondelectrode; perform a second measurement to obtain a transcapacitancesignal using the first and the second sensor electrodes; and adetermination module, the determination module configured to: generatethe combination signal by combining the first and the second resultingsignals; and compute an absolute capacitance signal from the combinationsignal, the transcapacitance signal, and a background capacitance. 2.The processing system of claim 1, wherein the first and the secondmodulated signals are identical waveforms.
 3. The processing system ofclaim 1, wherein the first and the second modulated signals haveidentical phases.
 4. The processing system of claim 1, wherein thesecond measurement is performed separately from the first measurement.5. The processing system of claim 1, wherein performing the secondmeasurement to obtain the transcapacitance signal comprises: selecting athird driving voltage amplitude for the first sensor electrode; drivingthe first electrode using a third modulated signal with the thirddriving voltage amplitude and holding the second electrode at a groundpotential; and receiving, simultaneously with the driving of the firstelectrode using the third modulated signal, a third resulting signalfrom the second electrode; and generating the transcapacitance signalfrom the third resulting signal.
 6. The processing system of claim 1,wherein the background capacitance is obtained from a calibrationmeasurement.
 7. The processing system of claim 1, wherein computing theabsolute capacitance signal from the combination signal and thetranscapacitance signal comprises additively combining thetranscapacitance signal with the combination signal.
 8. The processingsystem of claim 1, wherein the determination module is furtherconfigured to perform a low ground mass detection using the computedabsolute capacitance signal.
 9. The processing system of claim 1,wherein the determination module is further configured to: determineobject information using the computed absolute capacitance signal; andreport the object information to a host device, wherein the objectinformation triggers an interface action in a graphical user interfaceoperating on the host device.
 10. A capacitive sensing input devicecomprising: a plurality of sensor electrodes disposed in a sensorelectrode pattern, the plurality of sensor electrodes comprising a firstsensor electrode and a second sensor electrode; a sensor module, thesensor module configured to: perform a first measurement to obtain acombination signal using the first sensor electrode and the secondsensor electrode by: selecting a first driving voltage amplitude for thefirst sensor electrode and a second driving voltage amplitude for thesecond sensor electrode, wherein the second driving voltage amplitude isgreater than the first driving voltage amplitude; driving the firstelectrode using a first modulated signal with the first driving voltageamplitude and simultaneously driving the second electrode using a secondmodulated signal with the second driving voltage amplitude; andreceiving, simultaneously with the driving of the first and the secondelectrodes, a first resulting signal from the first electrode and asecond resulting signal from the second electrode; perform a secondmeasurement to obtain a transcapacitance signal using the first and thesecond sensor electrodes; and a determination module, the determinationmodule configured to: generate the combination signal by combining thefirst and the second resulting signals; and compute an absolutecapacitance signal from the combination signal, the transcapacitancesignal, and a background capacitance.
 11. The capacitive sensing inputdevice of claim 10, wherein the second measurement is performedseparately from the first measurement.
 12. The capacitive sensing inputdevice of claim 10, wherein performing the second measurement to obtainthe transcapacitance signal comprises: selecting a third driving voltageamplitude for the first sensor electrode; driving the first electrodeusing a third modulated signal with the third driving voltage amplitudeand holding the second electrode at a ground potential; and receiving,simultaneously with the driving of the first electrode using the thirdmodulated signal, a third resulting signal from the second electrode;and generating the transcapacitance signal from the third resultingsignal.
 13. The capacitive sensing input device of claim 10, wherein thebackground capacitance is obtained from a calibration measurement. 14.The capacitive sensing input device of claim 10, wherein computing theabsolute capacitance signal from the combination signal and thetranscapacitance signal comprises additively combining thetranscapacitance signal with the combination signal.
 15. The capacitivesensing input device of claim 10, wherein the determination module isfurther configured to: determine object information using the computedabsolute capacitance signal; and report the object information to a hostdevice, wherein the object information triggers an interface action in agraphical user interface operating on the host device.
 16. A method ofcapacitive sensing, the method comprising: performing a firstmeasurement to obtain a combination signal from a first sensor electrodeand a second sensor electrode among a plurality of sensor electrodes by:selecting a first driving voltage amplitude for the first sensorelectrode and a second driving voltage amplitude for the second sensorelectrode, wherein the second driving voltage amplitude is greater thanthe first driving voltage amplitude; driving the first electrode using afirst modulated signal with the first driving voltage amplitude andsimultaneously driving the second electrode using a second modulatedsignal with the second driving voltage amplitude; and receiving,simultaneously with the driving of the first and the second electrodes,a first resulting signal from the first electrode and a second resultingsignal from the second electrode; performing a second measurement toobtain a transcapacitance signal using the first and the second sensorelectrodes; generating the combination signal by combining the first andthe second resulting signals; and computing an absolute capacitancesignal from the combination signal, the transcapacitance signal, and abackground capacitance.
 17. The method of claim 16, wherein the secondmeasurement is performed separately from the first measurement.
 18. Themethod of claim 16, wherein performing the second measurement to obtainthe transcapacitance signal comprises: selecting a third driving voltageamplitude for the first sensor electrode; driving the first electrodeusing a third modulated signal with the third driving voltage amplitudeand holding the second electrode at a ground potential; and receiving,simultaneously with the driving of the first electrode using the thirdmodulated signal, a third resulting signal from the second electrode;and generating the transcapacitance signal from the third resultingsignal.
 19. The method of claim 16, wherein the background capacitanceis obtained from a calibration measurement.
 20. The method of claim 16,wherein computing the absolute capacitance signal from the combinationsignal and the transcapacitance signal comprises additively combiningthe transcapacitance signal with the combination signal.